Recyclable high-enthalpy-value solid-solid phase change material and preparation method thereof

Abstract

The invention discloses a recoverable high-enthalpy-value solid-solid phase change material and a preparation method thereof. Solid phase constraint of a liquid phase change material is achieved through a topological entanglement effect generated by a hydrogen bond network and polymer macromolecules. The coupling effect of the two limits the movement between low-molecular-weight phase change material molecules at the phase change temperature, and high-temperature solid-solid phase transformation is achieved. The solid-solid phase change material prepared by the method has a high enthalpy value and also has recoverability. In addition, due to the excellent light absorption capacity of the graphene oxide sheet, the graphene oxide sheet has a potential excellent function in the aspect of solar photo-thermal conversion.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, and in particular to a recyclable high-enthalpy solid-solid phase change material and its preparation method. Background Technology

[0002] Phase change materials (PCMs) have demonstrated significant application value in fields such as building energy conservation, electronic thermal management, smart textiles, and solar energy utilization due to their high energy storage density, isothermal phase change characteristics, cycle stability, and environmental friendliness. Especially in the renewable energy sector, PCMs can effectively alleviate the spatiotemporal mismatch between solar energy supply and demand through a sensible-latent heat synergistic storage mechanism. Their thermal buffering effect can effectively improve the efficiency of solar thermal systems while reducing equipment thermal stress.

[0003] Organic phase change materials (PCMs) have become a research focus due to their tunable phase transition temperature, non-toxicity, and chemical stability. However, traditional organic PCMs suffer from liquid-phase leakage caused by solid-liquid phase transitions. Currently, solid-solid PCM preparation strategies fall into two main categories: chemical and physical methods. Chemical methods can be categorized into four main systems: cross-linking systems, grafting systems, coordination systems, and block systems. Physical methods include microencapsulation technology, physical confinement, and physical coating. While physical methods are the mainstream research direction, pure physical methods still cannot completely eliminate the PCM leakage problem. Chemical methods can effectively solve the PCM leakage problem, but the preparation of solid-solid PCMs using chemical strategies inevitably reduces the enthalpy of the phase change material and may even lead to non-recyclability. Based on the above analysis, exploring high-enthalpy and recyclable phase change materials is of great significance.

[0004] The information disclosed in this background section is only intended to enhance the understanding of the background technology of this application, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0006] A method was proposed to achieve solid-state confinement of liquid phase change materials through the topological entanglement effect generated by hydrogen bonding networks and polymer macromolecules. The coupling effect between these two factors restricts the movement of low-molecular-weight phase change material molecules at the phase transition temperature, achieving a high-temperature solid-solid phase transition. The solid-solid phase change material prepared by this method has an enthalpy as high as 178 J·g. -1 -250 J·g -1 It is also recyclable; in addition, due to the excellent light absorption capacity of the included graphene oxide sheets, it has potential for excellent functions in solar photothermal conversion.

[0007] In some embodiments of this application, the method for preparing the recyclable high-enthalpy solid-solid phase change material of this application includes the following raw materials: graphene oxide (GO), polyethylene glycol (PEG), mannitol or erythritol, N-hydroxysuccinimide (NHS), 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), and adipic acid dihydrazide (AD). A method for preparing a recyclable high-enthalpy solid-solid phase change material includes the following steps: Step 1: Activate the oxygen-containing functional groups on the GO surface using NHS and EDC, thereby promoting the grafting of AD on the GO surface and forming GO@AD nanosheets containing multiple hydrogen bonds; Step 2: Preparation of dense hydrogen bond network polymer SPCM using stepwise polymerization: PEG and diisocyanate are added to an organic solvent to react, causing the terminal hydroxyl groups of PEG to react with the isocyanate groups (-NCO) to generate a prepolymer containing terminal -NCO groups; AD is added to the obtained prepolymer as a chain extender to carry out a polymerization reaction, resulting in a transparent polymer solution; the transparent polymer solution is poured into a mold for drying to solidify and shape the polymer film, and then demolded to obtain the polymer film; Step 3: Preparation of recyclable high-enthalpy solid-solid phase change material: First, prepare a hydrophilic polymer blend solution: Dissolve the dense hydrogen-bonded network polymer SPCM and PCM prepared in Step 2 together in a solvent to form a mixed aqueous solution; Second, disperse and composite the nano-reinforcing phase: Disperse the GO@AD nanosheets described in Step 1 in a solvent to obtain a GO@AD aqueous dispersion; Then, slowly add the GO@AD aqueous dispersion to the prepared SPCM and PCM mixed aqueous solution to react, allowing the GO@AD nanosheets to fully interact and composite with the hydrogen-bonded network in the SPCM matrix through the AD grafted on their surface; Next, heat and stir until the water evaporates, and the material becomes viscous or pasty; Finally, dry and solidify the product.

[0008] In some embodiments of this application, step one specifically includes the following steps: (1) First, GO is dispersed in deionized water to form a dispersion, wherein the concentration of GO in the dispersion is 0.5-2 mg / mL, and GO is dispersed by ultrasonic treatment; (2) Subsequently, EDC and NHS are added to the dispersion in sequence, wherein the mass-volume ratio of EDC to NHS is (5-7):(15-20), and the mixture is stirred at room temperature for 15-20 minutes to activate the oxygen-containing functional groups on the GO surface. (3) Add AD to the activated GO dispersion in step (2), wherein the amount of AD added is 10-20 mg / mL, and stir continuously at 25°C for 24-36 hours, so that AD is grafted onto the GO surface through amidation reaction to form GO@AD nanocomposite material with multiple hydrogen bond structure. (4) After the reaction is completed, the reaction mixture is centrifuged and washed repeatedly with deionized water to remove unreacted substances and byproducts; finally, the washed product is freeze-dried for 48-72 hours to obtain the GO@AD nanosheets.

[0009] In some embodiments of this application, step two specifically includes the following steps: (1) First, PEG is pretreated by placing it in a vacuum drying oven and dehydrating it at 110℃-120℃ for 3-4 hours to completely remove the moisture contained inside. After treatment, the dehydrated PEG is transferred to an environment filled with dry nitrogen for storage in preparation for subsequent use to prevent it from absorbing moisture again. (2) Next, a prepolymerization reaction is carried out; under a dry inert atmosphere, the PEG and diisocyanate treated in step (1) are added to an organic solvent to form a uniform mixed solution; then, the mixed solution is stirred at a temperature of 60°C-80°C for 3-5 hours to allow the terminal hydroxyl groups of PEG to react with the isocyanate groups (-NCO) to generate a prepolymer containing terminal -NCO groups; (3) Next, chain extension and final polymerization reaction are carried out: AD as a chain extender is added to the prepolymer solution obtained in step (2), the temperature of the reaction system is adjusted and maintained at 40°C-60°C, and the reaction is stirred for 8-10 hours. During this process, the active hydrogen on the AD molecule reacts with the -NCO group at the end of the prepolymer to realize chain extension and cross-linking, thereby completing the final polymerization reaction and obtaining a transparent polymer solution. (4) Post-processing: The transparent polymer solution obtained in step (3) is poured into a polytetrafluoroethylene mold. Then, the mold is placed in a vacuum drying oven at 60°C-80°C and dried for 24-36 hours before being demolded to obtain the desired polymer film with uniform structure.

[0010] In some embodiments of this application, the average molecular weight of PEG in step (2) includes, but is not limited to, 6000, 8000, 10000, and 20000.

[0011] In some embodiments of this application, the diisocyanate in step (2) is hexamethylene diisocyanate or isophorone diisocyanate.

[0012] In some embodiments of this application, the organic solvent in step (2) includes, but is not limited to, N,N-dimethylformamide and N,N-dimethylacetamide.

[0013] In some embodiments of this application, in step two (2), the molar ratio of PEG to diisocyanate is 1:2 to 1:4.

[0014] In some embodiments of this application, step three specifically involves the following steps: (1) First, prepare the hydrophilic polymer blend solution: dissolve the dense hydrogen bond network polymers SPCM and PCM from step two in 10-20 mL of deionized water, wherein the mass ratio of SPCM to PCM is (1-2):(8-9). Maintain the solution at a temperature of 90°C-100°C and under continuous stirring for 30 minutes to form a uniform and clear mixed aqueous solution. (2) Next, the dispersion and composite of the nano-reinforced phase are carried out: take an appropriate amount of GO@AD nanosheets as described in step one, disperse them in an appropriate amount of deionized water, and treat them with ultrasonic treatment in a water bath for 15-30 minutes to obtain a uniformly dispersed GO@AD aqueous dispersion. (3) Subsequently, the GO@AD aqueous dispersion was slowly added to the PCM and SPCM mixed aqueous solution prepared in step (1), and the reaction was continuously stirred at a temperature of 60°C-90°C for 1-2 hours, so that the GO@AD nanosheets could fully interact with the hydrogen bond network in the SPCM matrix through the AD grafted on its surface, and achieve uniform nanoscale composite. (4) Next, concentration and preliminary shaping are carried out: the composite system of step (3) is continuously heated and stirred until the water evaporates and the material presents a uniform viscous or paste-like state. (5) Finally, perform step-by-step drying and curing: transfer the product obtained in step (4) into a pre-prepared silicone mold and perform drying and curing.

[0015] In some embodiments of this application, in step three (5), the drying and curing is a step-by-step drying and curing process, specifically: First stage drying: Place the mold in an oven at 70°C-80°C and dry for 2-4 hours. This is intended to quickly remove any remaining small amount of moisture and promote the initial shaping of the material. Second stage drying: Transfer the mold to an oven at 40°C-60°C and continue drying for 18-36 hours; this process helps to fully build and stabilize the internal hydrogen bond network structure of the material, reduce internal stress, and obtain a final composite phase change material with uniform structure and stable performance.

[0016] In some embodiments of this application, the PCM in step (3) includes, but is not limited to, one or more of PEG with an average molecular weight of 6000-20000, erythritol, and mannitol.

[0017] In other embodiments of this application, recyclable high-enthalpy solid-solid PCM prepared by the above method is also involved.

[0018] Compared with existing solid-solid PCMs, the recyclable high-enthalpy solid-solid PCM of this application has the following advantages and beneficial effects: (1) The recyclable solid-solid PCM prepared in this application can maintain solid-solid phase transition at high temperature due to the strong hydrogen bond network and the entanglement of the polymer. Due to the structural design of this linear molecule, the material can be recycled.

[0019] (2) The recyclable solid-solid phase change material prepared in this application has a high enthalpy value due to its high phase change material content and high crystallinity.

[0020] (3) The recyclable solid-solid PCM preparation method described in this application mainly utilizes an aqueous solution processing method, which uses less organic solvent and has the advantages of low cost and easy industrialization.

[0021] (4) The recyclable solid-solid PCM prepared in this application can be used for solar energy storage due to the broad spectral absorption of GO and the high phase transition enthalpy of solid-solid PCM. Attached Figure Description

[0023] Figure 1 This is the differential scanning calorimetry curve of the recyclable high-enthalpy solid-solid phase change material prepared in Example 1 of this application; Figure 2 This is the rheological property curve of the recyclable high-enthalpy solid-solid phase change material prepared in Example 1 of this application; Detailed Implementation

[0024] The present application will be described in detail below with reference to the embodiments thereof, but the present application is not limited to these embodiments.

[0025] Unless otherwise specified, the raw materials and catalysts used in the embodiments of this application were all purchased commercially.

[0026] Differential scanning calorimetry (DSC) curves of recyclable high-enthalpy solid-solid phase change materials were obtained under nitrogen atmosphere. Rheological property curves were obtained using a torque rheometer at a specified constant frequency of 1 Hz.

[0027] Example 1 A recyclable high-enthalpy solid-solid phase change material, GO@AD / SPCM / PEG, was prepared using an aqueous solution blending method. The preparation process is as follows: (1) First, take 1g of dense hydrogen bond network polymer SPCM and 9g of PEG10000 and dissolve them together in 50ml of deionized water. Stir continuously at 90°C for 30 minutes.

[0028] (2) Then weigh 1g of GO@AD nanosheets, disperse them in 30ml of deionized water, and sonicate them in a water bath for 30 minutes to obtain a uniformly dispersed GO@AD aqueous dispersion.

[0029] (3) Add the GO@AD aqueous dispersion obtained in step 2) to the PEG and SPCM mixed aqueous solution prepared in step 1) and stir continuously at 60°C for 1 hour.

[0030] (4) Next, stir until the water evaporates to a thick consistency, then pour the material into a silicone mold and place it in an 80°C oven for 2 hours, then transfer it to a 40°C oven for 36 hours until completely dry.

[0031] The recyclable high-enthalpy solid-solid phase change material obtained in this embodiment has a phase change enthalpy of 178 J·g. -1 The differential scanning calorimetry curve is as follows: Figure 1 As shown. Its rheological curves at 80°C-150°C are as follows. Figure 2 As shown, the energy storage modulus is always higher than the loss modulus, confirming the solid-solid phase transition process of the recyclable high-enthalpy solid-solid PCM at high temperatures.

[0032] Example 2 A method for preparing GO@AD / SPCM / erythritol recyclable high-enthalpy solid-solid PCM using an aqueous solution blending method is described below: (1) First, take 2g of dense hydrogen bond network polymer SPCM and 8g of erythritol, dissolve them together in 30ml of deionized water, and stir continuously at 70°C for 30 minutes.

[0033] (2) Then weigh 1g of GO@AD nanosheets, disperse them in 30ml of deionized water, and sonicate them in a water bath for 30 minutes to obtain a uniformly dispersed GO@AD aqueous dispersion.

[0034] (3) Add the GO@AD aqueous dispersion obtained in step 2) to the erythritol and SPCM mixed aqueous solution prepared in step 1), and stir continuously at 70°C for 1 hour.

[0035] (4) Next, stir until the water evaporates to a thick consistency, then pour the material into a silicone mold and place it in a 70°C oven for 2 hours, then transfer it to a 60°C oven for 28 hours until completely dry.

[0036] The recoverable high-enthalpy solid-solid PCM phase transition enthalpy value obtained in this embodiment is 246 J·g. -1 .

[0037] Example 3 A method for preparing GO@AD / SPCM / recoverable high-enthalpy solid-solid PCM using aqueous solution blending is described below: (1) First, take 1g of dense hydrogen bond network polymer SPCM and 9g of mannitol, dissolve them together in 30ml of deionized water, and stir continuously at 60°C for 30 minutes.

[0038] (2) Then weigh 1g of GO@AD nanosheets, disperse them in 30ml of deionized water, and sonicate them in a water bath for 30 minutes to obtain a uniformly dispersed GO@AD aqueous dispersion.

[0039] (3) Add the GO@AD aqueous dispersion obtained in step 2) to the erythritol and SPCM mixed aqueous solution prepared in step 1), and stir continuously at 60°C for 1 hour.

[0040] (4) Next, stir until the water evaporates to a thick consistency, then pour the material into a silicone mold and place it in a 70 °C oven for 2 hours, then transfer it to a 60 °C oven for 28 hours until completely dry.

[0041] The recoverable high-enthalpy solid-solid PCM phase transition enthalpy value obtained in this embodiment is 250 J·g. -1 .

[0042] Example 4 In some embodiments of this application, the preparation of the dense hydrogen bond network polymer SPCM specifically includes the following steps: (1) First, PEG is pretreated by placing it in a vacuum drying oven and dehydrating it at 110℃-120℃ for 3-4 hours to completely remove the moisture contained inside. After treatment, the dehydrated PEG is transferred to an environment filled with dry nitrogen for storage in preparation for subsequent use to prevent it from absorbing moisture again. (2) Next, a prepolymerization reaction is carried out; under a dry inert atmosphere, the PEG and diisocyanate treated in step (1) are added to an organic solvent to form a uniform mixed solution; then, the mixed solution is stirred at a temperature of 60°C-80°C for 3-5 hours to allow the terminal hydroxyl groups of PEG to react with the isocyanate groups (-NCO) to generate a prepolymer containing terminal -NCO groups; (3) Next, chain extension and final polymerization reaction are carried out: AD as a chain extender is added to the prepolymer solution obtained in step (2), the temperature of the reaction system is adjusted and maintained at 40°C-60°C, and the reaction is stirred for 8-10 hours. During this process, the active hydrogen on the AD molecule reacts with the -NCO group at the end of the prepolymer to realize chain extension and cross-linking, thereby completing the final polymerization reaction and obtaining a transparent polymer solution. (4) Post-processing: The transparent polymer solution obtained in step (3) is poured into a polytetrafluoroethylene mold. Then, the mold is placed in a vacuum drying oven at 60°C-80°C and dried for 24-36 hours before being demolded to obtain the desired polymer film with uniform structure. In step two (2), the molar ratio of PEG to diisocyanate is 1:2 to 1:4; In step two (3), the molar ratio of prepolymer to chain extender is 1:1 to 1:3.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a recyclable high-enthalpy solid-solid phase change material, characterized in that, The raw materials include: graphene oxide (GO), polyethylene glycol (PEG), mannitol or erythritol, N-hydroxysuccinimide (NHS), 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), and adipic acid dihydrazide (AD). The preparation method specifically includes the following steps: Step 1: Activate the oxygen-containing functional groups on the GO surface using NHS and EDC, thereby promoting the grafting of AD on the GO surface and forming GO@AD nanosheets containing multiple hydrogen bonds; Step 2: Preparation of dense hydrogen bond network polymer SPCM using stepwise polymerization: PEG and diisocyanate are added to an organic solvent to react, causing the terminal hydroxyl groups of PEG to react with the isocyanate groups (-NCO) to generate a prepolymer containing terminal -NCO groups; AD is added to the obtained prepolymer as a chain extender to carry out a polymerization reaction, resulting in a transparent polymer solution; the transparent polymer solution is poured into a mold for drying to solidify and shape the polymer film, and then demolded to obtain the polymer film; Step 3: Preparation of recyclable high-enthalpy solid-solid phase change material: First, prepare a hydrophilic polymer blend solution: Dissolve the dense hydrogen-bonded network polymer SPCM and PCM prepared in Step 2 together in a solvent to form a mixed aqueous solution; Second, disperse and composite the nano-reinforcing phase: Disperse the GO@AD nanosheets described in Step 1 in a solvent to obtain a GO@AD aqueous dispersion; Then, slowly add the GO@AD aqueous dispersion to the prepared SPCM and PCM mixed aqueous solution to react, allowing the GO@AD nanosheets to fully interact and composite with the hydrogen-bonded network in the SPCM matrix through the AD grafted on their surface; Next, heat and stir until the water evaporates, and the material becomes viscous or pasty; Finally, dry and solidify the product.

2. The method for preparing a recyclable high-enthalpy solid-solid phase change material according to claim 1, characterized in that, Step one specifically includes the following steps: (1) First, GO is dispersed in deionized water to form a dispersion, wherein the concentration of GO in the dispersion is 0.5-2 mg / mL, and GO is dispersed by ultrasonic treatment; (2) Subsequently, EDC and NHS are added to the dispersion in sequence, wherein the mass-volume ratio of EDC to NHS is (5-7):(15-20), and the mixture is stirred at room temperature for 15-20 minutes to activate the oxygen-containing functional groups on the GO surface. (3) Add AD to the activated GO dispersion in step (2), wherein the amount of AD added is 10-20 mg / mL, and stir continuously at 25°C for 24-36 hours, so that AD is grafted onto the GO surface through amidation reaction to form GO@AD nanocomposite material with multiple hydrogen bond structure. (4) After the reaction is completed, the reaction mixture is centrifuged and washed repeatedly with deionized water to remove unreacted substances and byproducts; finally, the washed product is freeze-dried for 48-72 hours to obtain the GO@AD nanosheets.

3. The method for preparing a recyclable high-enthalpy solid-solid phase change material according to claim 1, characterized in that, Step two specifically includes the following steps: (1) First, PEG is pretreated by placing it in a vacuum drying oven and dehydrating it at 110℃-120℃ for 3-4 hours to completely remove the moisture contained inside. After treatment, the dehydrated PEG is transferred to an environment filled with dry nitrogen for storage in preparation for subsequent use to prevent it from absorbing moisture again. (2) Next, a prepolymerization reaction is carried out; under a dry inert atmosphere, the PEG and diisocyanate treated in step (1) are added to an organic solvent to form a uniform mixed solution; then, the mixed solution is stirred at a temperature of 60°C-80°C for 3-5 hours to allow the terminal hydroxyl groups of PEG to react with the isocyanate groups (-NCO) to generate a prepolymer containing terminal -NCO groups; (3) Next, chain extension and final polymerization reaction are carried out: AD as a chain extender is added to the prepolymer solution obtained in step (2), the temperature of the reaction system is adjusted and maintained at 40°C-60°C, and the reaction is stirred for 8-10 hours. During this process, the active hydrogen on the AD molecule reacts with the -NCO group at the end of the prepolymer to realize chain extension and cross-linking, thereby completing the final polymerization reaction and obtaining a transparent polymer solution. (4) Post-processing: The transparent polymer solution obtained in step (3) is poured into a polytetrafluoroethylene mold. Then, the mold is placed in a vacuum drying oven at 60°C-80°C and dried for 24-36 hours before being demolded to obtain the desired polymer film with uniform structure.

4. The method for preparing a recyclable high-enthalpy solid-solid phase change material according to claim 1, characterized in that, The average molecular weight of PEG in step (2) of the second step is one of 6000, 8000, 10000, and 20000.

5. The method for preparing a recyclable high-enthalpy solid-solid phase change material according to claim 1, characterized in that, The diisocyanate in step two (2) is hexamethylene diisocyanate or isophorone diisocyanate; the organic solvent in step two (2) is N,N-dimethylformamide or N,N-dimethylacetamide.

6. The method for preparing a recyclable high-enthalpy solid-solid phase change material according to claim 1, characterized in that, The PCM in step three (3) includes, but is not limited to, one or more of PEG with an average molecular weight of 6000-20000, erythritol, and mannitol.

7. The method for preparing a recyclable high-enthalpy solid-solid phase change material according to claim 1, characterized in that, In step two (2), the molar ratio of PEG to diisocyanate is 1:2 to 1:

4.

8. The method for preparing a recyclable high-enthalpy solid-solid phase change material according to claim 1, characterized in that, The specific steps of step three are as follows: (1) First, prepare the hydrophilic polymer blend solution: dissolve the dense hydrogen bond network polymers SPCM and PCM from step two in 10-20 mL of deionized water, wherein the mass ratio of SPCM to PCM is (1-2):(8-9). Maintain the solution at a temperature of 90°C-100°C and under continuous stirring for 30 minutes to form a uniform and clear mixed aqueous solution. (2) Next, the dispersion and composite of the nano-reinforced phase are carried out: take an appropriate amount of GO@AD nanosheets as described in step one, disperse them in an appropriate amount of deionized water, and treat them with ultrasonic treatment in a water bath for 15-30 minutes to obtain a uniformly dispersed GO@AD aqueous dispersion. (3) Subsequently, the GO@AD aqueous dispersion was slowly added to the PCM and SPCM mixed aqueous solution prepared in step (1), and the reaction was continuously stirred at a temperature of 60°C-90°C for 1-2 hours, so that the GO@AD nanosheets could fully interact with the hydrogen bond network in the SPCM matrix through the AD grafted on its surface, and achieve uniform nanoscale composite. (4) Next, concentration and preliminary shaping are carried out: the composite system of step (3) is continuously heated and stirred until the water evaporates and the material presents a uniform viscous or paste-like state. (5) Finally, perform step-by-step drying and curing: transfer the product obtained in step (4) into a pre-prepared silicone mold and perform drying and curing.

9. The method for preparing a recyclable high-enthalpy solid-solid phase change material according to claim 8, characterized in that, In step three (5), the drying and curing is a step-by-step drying and curing process, specifically as follows: First stage drying: Place the mold in an oven at 70°C-80°C and dry for 2-4 hours. This is intended to quickly remove any remaining small amount of moisture and promote the initial shaping of the material. The second stage of drying involves transferring the mold into an oven at 40°C-60°C and continuing to dry for 18-36 hours. This helps to fully construct and stabilize the internal hydrogen bond network structure of the material, reduce internal stress, and obtain a final composite phase change material with uniform structure and stable performance.

10. A recyclable high-enthalpy solid-solid phase change material, characterized in that, It is prepared by the preparation method described in any one of claims 1-9.

Images