A reworkable and self-healing polyurethane solid-solid phase change material and a preparation method thereof

Abstract

The application discloses a kind of reworkable and self-repairing polyurethane solid-solid phase change material and preparation method thereof, comprising: under argon or nitrogen atmosphere, polyethylene glycol is added to reactor for water removal treatment, under certain temperature and stirring speed, diisocyanate is dissolved in solvent and then added to reactor, catalyst is added, and pre-polymer is obtained by reaction;Temperature is adjusted, butanedione oxime and metal compound are dissolved in solvent respectively and then added to reactor, continue to react, pentaerythritol is dissolved in solvent and then added to reactor, and polyurethane solution is obtained by stirring;Polyurethane solution is poured into polytetrafluoroethylene mold, dried in oven, and reworkable and self-repairing polyurethane solid-solid phase change material is obtained.The oxime-urethane bond, metal coordination bond and hydrogen bond are introduced into the polyurethane solid-solid phase change material, and the obtained polyurethane solid-solid phase change material not only has good phase change performance and mechanical properties, but also has reworkability and self-repairing performance.

Description

Technical Field

[0001] This invention belongs to the field of phase change material technology. More specifically, this invention relates to a reprocessable and self-healing polyurethane solid-solid phase change material and its preparation method. Background Technology

[0002] Polyurethane solid-solid phase change materials (PCMs) not only effectively solve the problems of poor stability, easy leakage, and the need for additional encapsulation inherent in solid-liquid PCMs, but also possess advantages such as good thermal stability, high mechanical strength, and wear and corrosion resistance. Furthermore, the phase change enthalpy and temperature can be controlled by adjusting the ratio of soft to hard segments, making it one of the most promising PCMs in recent years. However, a problem remains: the permanent cross-linked network in its structure causes a significant decrease in its service life and stability once damaged; moreover, discarded polyurethane PCMs cannot be recycled and reprocessed, leading to environmental pollution and resource waste, seriously hindering its long-term sustainable development. To address these issues, introducing reversible dynamic bonds to construct a dynamically cross-linked polyurethane network is an effective solution.

[0003] Dynamic bonds are chemical bonds based on reversible chemical reactions. They can undergo reversible "breakage" and "recombination" under certain external conditions (such as heat, pH, light, and catalysts). Introducing dynamic bonds into polyurethane solid-solid phase change materials to construct dynamic cross-linked networks can endow them with self-healing and reprocessing properties, thereby improving their stability and increasing their service life. This is of great significance for promoting the development of sustainable and environmentally friendly materials. Summary of the Invention

[0004] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0005] To achieve these objectives and other advantages of the present invention, a reprocessable and self-healing polyurethane solid-solid phase change material is provided, wherein the raw materials for preparing the reprocessable and self-healing polyurethane solid-solid phase change material include: polyethylene glycol, diisocyanate, dimethylglyoxime, metal compound, pentaerythritol, catalyst and solvent.

[0006] Preferably, the molar ratio of polyethylene glycol, diisocyanate, dimethylglyoxime, and pentaerythritol is 3-5:7-8:1-3:0.5-1; and the molar ratio of the metal compound and dimethylglyoxime is 1:1-4.

[0007] Preferably, the polyethylene glycol is one or more of polyethylene glycol 2000, polyethylene glycol 4000, polyethylene glycol 6000, polyethylene glycol 8000 and polyethylene glycol 10000.

[0008] Preferably, the diisocyanate is one or more selected from hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

[0009] Preferably, the metal compound is one or more of copper chloride, zinc chloride, nickel chloride, ferrous chloride, ferric chloride, copper nitrate, zinc nitrate, nickel nitrate, ferrous nitrate, and ferric nitrate.

[0010] Preferably, the catalyst is dibutyltin dilaurate; and the solvent is N,N-dimethylformamide, tetrahydrofuran, or dimethyl sulfoxide.

[0011] A method for preparing a reprocessable and self-healing polyurethane solid-solid phase change material as described above includes the following steps:

[0012] Step 1: Under an argon or nitrogen atmosphere, polyethylene glycol is added to the reactor for dehydration treatment. Then, at a certain temperature and stirring speed, diisocyanate is dissolved in a solvent and added to the reactor. Next, a catalyst is added, and the reaction is carried out for 3-5 hours to obtain the prepolymer.

[0013] Step 2: Adjust the temperature, dissolve the dimethylglyoxime and the metal compound in solvents respectively, and then add them to the reactor containing the prepolymer from Step 1. Continue the reaction for 2-4 hours. Then dissolve pentaerythritol in solvents and add it to the reactor. Continue stirring for 10-30 minutes to obtain a polyurethane solution.

[0014] Step 3: Pour the polyurethane solution obtained in Step 2 into a polytetrafluoroethylene mold, place it in an oven to dry, and obtain a reprocessable and self-healing polyurethane solid-solid phase change material.

[0015] Preferably, the entire reaction process is carried out under an argon or nitrogen atmosphere.

[0016] Preferably, the solvent needs to be prepared before use. Dehydration of molecular sieves takes at least 10 days.

[0017] Preferably, an appropriate amount of solvent is added to the reactor during the reaction after the catalyst is added to reduce the reaction viscosity.

[0018] Preferably, in step one, the dehydration treatment is performed by vacuum drying at 100–120°C for 2–4 hours; the temperature is 70–85°C; the stirring speed is 200–250 rpm; the mass-to-volume ratio of diisocyanate to solvent is 1–2 g: 4–10 mL; and the amount of catalyst used is 0.5–2% of the total mass of polyethylene glycol and diisocyanate.

[0019] Preferably, in step two, the temperature is adjusted to 60-70°C; the mass-to-volume ratio of dimethylglyoxime to solvent is 0.1-1g:4-10mL; the mass-to-volume ratio of metal compound to solvent is 0.1-1g:4-10mL; and the mass-to-volume ratio of pentaerythritol to solvent is 0.1-1g:4-10mL.

[0020] Preferably, in step three, the drying temperature is 50–80°C and the drying time is 20–30 hours.

[0021] Preferably, step two is replaced by: adjusting the temperature, dissolving dimethylglyoxime and anhydrous copper chloride in solvents and adding them to the reactor, continuing the reaction for 2-4 hours, then radio frequency treatment for 5-20 minutes using radio frequency equipment, then dissolving anhydrous ferrous chloride in solvents and adding it to a three-necked flask, continuing the reaction for 1-2 hours, then dissolving pentaerythritol in solvents and adding it to the reactor, continuing stirring for 10-30 minutes to obtain a polyurethane solution.

[0022] Preferably, the power of the radio frequency processing is 5-8kW, the frequency is 27MHz, the electrode spacing is 10-30cm, and the molar ratio of anhydrous copper chloride and anhydrous ferrous chloride is 0.5-0.9:0.1-0.5.

[0023] The present invention has at least the following beneficial effects: The present invention provides a reprocessable and self-healing polyurethane solid-solid phase change material and its preparation method. Dynamic oxime-urethane bonds, metal coordination bonds and hydrogen bonds are introduced into the cross-linked polyurethane solid-solid phase change material system to obtain a shape-stable dynamic cross-linked polyurethane solid-solid phase change material. Under the synergistic effect of the triple dynamic bonds, the material not only has good phase change performance and mechanical properties, but also reprocessability and self-healing properties. It can be recycled and is environmentally friendly.

[0024] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0025] Figure 1 Preparation of Cu in Example 1 of the present invention 2+ -Reaction mechanism diagram of OUPCMs;

[0026] Figure 2 Cu prepared in Example 1 of this invention 2+ -Infrared absorption spectra of OUPCMs and their raw materials;

[0027] Figure 3 Cu prepared in Example 1 of this invention 2+ -Elemental spectral images of OUPCMs;

[0028] Figure 4 Cu prepared in Example 1 of this invention 2+ XRD patterns of -OUPCMs and PEG 4000;

[0029] Figure 5 Cu prepared in Example 1 of this invention 2+ - DSC curves of OUPCMs and PEG 4000;

[0030] Figure 6 Cu prepared in Example 1 of this invention 2+ - A schematic diagram of the reprocessing process of OUPCMs;

[0031] Figure 7 Cu prepared in Example 1 of this invention 2+ -OUPCMs, after multiple reprocessing steps, are combined with the original Cu 2+ -Infrared spectra of OUPCMs;

[0032] Figure 8 Cu prepared in Example 1 of this invention 2+ -OUPCMs, after five reprocessing steps, are in harmony with the original Cu. 2+ - Stress-strain curves of OUPCMs;

[0033] Figure 9 Cu prepared in Example 1 of this invention 2+ -OUPCMs, after multiple reprocessing steps, are combined with the original Cu 2+ - DSC curve of OUPCMs, where S represents Cu 2+ -OUPCMs;

[0034] Figure 10 Cu prepared in Example 1 of this invention 2+ - Optical microscopic images of scratch self-healing of OUPCMs before and after repair, A is before repair, B is after repair;

[0035] Figure 11 Cu prepared in Example 1 of this invention 2+ -OUPCMs self-healing and original Cu 2+ - Stress-strain curves of OUPCMs;

[0036] Figure 12 The image shows a reprocessed physical sample of BDO-PCMs prepared in Comparative Example 1. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0038] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0039] The materials used in the following examples are: polyethylene glycol (PEG, Mn = 4000 g / mol, Kelong), hexamethylene diisocyanate (HDI, Aladdin), dimethylglyoxime (DMG, Aladdin), anhydrous copper chloride (CuCl2, Kelong), anhydrous zinc chloride (ZnCl2, Kelong), anhydrous nickel chloride (NiCl2, Kelong), anhydrous ferrous chloride (FeCl2, Kelong), pentaerythritol (PTOL, Aladdin), dibutyltin dilaurate (DBTDL, Kelong), and N,N-dimethylformamide (DMF, Kelong).

[0040] Example 1

[0041] A reprocessable and self-healing polyurethane solid-solid phase change material is prepared from the following raw materials: polyethylene glycol (PEG, Mn = 4000 g / mol, 16 g, 4 moles), hexamethylene diisocyanate (HDI, 1.3039 g, 7.6 moles), dimethylglyoxime (DMG, 0.2323 g, 2 moles), anhydrous copper chloride (CuCl2, 0.1345 g, 1 mole), pentaerythritol (PTOL, 0.1090 g, 0.8 moles), dibutyltin dilaurate (DBTDL, 0.18 g, 1 wt%), and N,N-dimethylformamide (DMF, 60 mL).

[0042] The preparation method of the reprocessable and self-healing polyurethane solid-solid phase change material as described above includes the following steps:

[0043] Step 1: Under an argon atmosphere, polyethylene glycol is added to a three-necked flask and dried in a vacuum oven at 110°C for 3 hours. Then, the three-necked flask is placed in a thermostatic magnetic stirrer with the temperature set to 80°C and the speed set to 220 rpm. Hexamethylene diisocyanate is dissolved in 5 mL of N,N-dimethylformamide and added to the three-necked flask. Next, dibutyltin dilaurate is added as a catalyst, and the reaction is carried out for 4 hours. During the reaction, an additional 40 mL of N,N-dimethylformamide is added to reduce the viscosity of the reaction, thus obtaining the prepolymer PEG-HDI.

[0044] Step 2: Set the temperature of the thermostatic magnetic stirrer to 65℃ and maintain the speed at 220 rpm. Dissolve dimethylglyoxime and anhydrous copper chloride in 5 mL of N,N-dimethylformamide and add them to the three-necked flask containing PEG-HDI from Step 1. Continue the reaction for 3 hours. Then, dissolve pentaerythritol in 5 mL of N,N-dimethylformamide and add it to the three-necked flask. Continue stirring for 20 minutes to obtain a polyurethane solution.

[0045] Step 3: Pour the polyurethane solution obtained in Step 2 into a polytetrafluoroethylene mold and dry it in a 60℃ oven for 24 hours to obtain a reprocessable and self-healing polyurethane solid-solid phase change material, namely Cu. 2+ -OUPCMs.

[0046] In this embodiment, Cu is prepared. 2+ -The reaction mechanism diagram of OUPCMs is shown below. Figure 1 As shown.

[0047] Figure 2 Cu prepared in this embodiment 2+ -Infrared absorption spectra of OUPCMs and their raw materials. It can be seen that HDI at 2275 cm⁻¹... -1 There is a very distinct characteristic peak at this point, which is due to its -NCO stretching vibration. Cu... 2+ -2275 cm⁻¹ did not appear in the spectrum of -OUPCMs -1 The characteristic band at this point is because the -N=C=O in HDI has completely reacted. Furthermore, Cu... 2+ Two new characteristic peaks also appeared in the spectrum of -OUPCMs: 1718 cm⁻¹ -1 The stretching vibration peak at -C=O and 1518 cm⁻¹ -1 The bending vibration peak of NH indicates the formation of urethane bonds (-NH-COO-). Based on the above analysis, it can be preliminarily determined that a polyurethane solid-solid phase change material with PEG 4000 as the soft segment has been successfully prepared.

[0048] Figure 3 Cu prepared in this embodiment 2+ -Elemental spectrum image of OUPCMs. It can be seen that C, O, N, and Cu elements are uniformly distributed in Cu. 2+ -The surface of OUPCMs, Cu element in Cu 2+ The uniform distribution of -OUPCMs indicates that the introduced Cu element did not show significant aggregation.

[0049] Figure 4 Cu prepared in this embodiment 2+XRD patterns of Cu²⁺-OUPCMs and PEG 4000. It can be seen that Cu²⁺-OUPCMs exhibit two diffraction peaks similar to pure PEG at approximately 19.43° and 23.58°, with essentially the same diffraction lines, diffraction angles, and interplanar spacing, indicating that it has the same crystal form and unit cell as PEG. This is because in Cu²⁺... 2+ - In PUPCMs, the soft segment of PEG has a large molecular weight, good symmetry, and a high degree of phase separation between soft and hard segments, which allows it to be well enriched. Therefore, it exhibits a crystal structure similar to that of pure PEG and shows melting and crystallization behavior similar to that of pure PEG during phase transition.

[0050] Figure 5 Cu prepared in this embodiment 2+ - DSC curves of OUPCMs and PEG 4000. It can be seen that Cu 2+ -OUPCMs, like pure PEG, exhibit good heat storage performance, showing endothermic and exothermic peaks during temperature rise and fall. This is mainly due to the melting and crystallization of the PEG soft segments in the polyurethane chain during phase transition. The formation of hard segment microdomains and cross-linked networks restricts PEG crystallization, reducing its crystallinity, thus resulting in the synthesized Cu... 2+ -OUPCMs have a lower enthalpy value compared to pure PEG, but still have a certain phase change heat storage capacity.

[0051] Figure 6 Cu prepared in this embodiment 2+ -A schematic diagram of the reprocessing process of OUPCMs, showing the Cu... 2+ -OUPCMs samples were shredded and then hot-pressed at 120℃ and 10MPa for 20 min. The shredded Cu 2+ -OUPCMs samples can yield a new, uniform, and flat film. This is because under thermo-pressing conditions, the polymer molecular chains move faster, causing the broken oxime-urethane bonds and hydrogen bonds to come into contact with and rearrange with the metal coordination bonds, ultimately forming a complete film again. For example... Figure 7 As shown, the infrared spectra of the material after 1, 3, and 5 reprocessing cycles are basically consistent with the original spectra, indicating that hot pressing did not damage the chemical structure of the material. Figure 8 As shown, Cu 2+ -OUPCMs have a tensile strength of 14.08 MPa, and the Cu after 5 cycles of reprocessing... 2+ - The tensile strength of the OUPCMs is 13.98 MPa, recovering to 99.29% of its original strength. For example... Figure 9 As shown, Cu after 1, 3, and 5 reprocessing steps 2 +-OUPCMs still exhibited endothermic and exothermic peaks that were essentially consistent with the original sample, indicating that their phase change heat storage capacity was no different from that of the original sample. In summary, this demonstrates that the Cu of the present invention... 2+ -OUPCMs have good reprocessability and can be recycled multiple times.

[0052] Use a blade on Cu 2+ -A scratch was made on the surface of the OUPCMs sample and observed under an optical microscope. Figure 10 A), then place it on a 75℃ hot plate for 10 minutes to repair before observation. Figure 10 B) It can be seen that the Cu of the present invention 2+ -OUPCMs have excellent self-healing properties.

[0053] Cu 2+ -After completely cutting the OUPCMs standard dumbbell-shaped spline in the middle, the two sections are brought into full contact, and then placed in a 90℃ oven for heat repair for 25 hours. Its tensile strength is then tested. For example... Figure 11 As shown, the repaired Cu 2+ - The tensile strength of OUPCMs is 12.86 MPa, and the self-healing efficiency is 91.34%; the formula for calculating the self-healing efficiency is as follows:

[0054] Self-healing efficiency (%) = (Tensile strength after repair / Original tensile strength) × 100%

[0055] Example 2

[0056] A reprocessable and self-healing polyurethane solid-solid phase change material is prepared from the following raw materials: polyethylene glycol (PEG, Mn = 4000 g / mol, 16 g, 4 moles), hexamethylene diisocyanate (HDI, 1.3039 g, 7.6 moles), dimethylglyoxime (DMG, 0.2323 g, 2 moles), anhydrous zinc chloride (ZnCl2, 0.1364 g, 1 mole), pentaerythritol (PTOL, 0.1090 g, 0.8 moles), dibutyltin dilaurate (DBTDL, 0.18 g, 1 wt%), and N,N-dimethylformamide (DMF, 60 mL).

[0057] The preparation method of the reprocessable and self-healing polyurethane solid-solid phase change material as described above includes the following steps:

[0058] Step 1: Under an argon atmosphere, polyethylene glycol is added to a three-necked flask and dried in a vacuum oven at 110°C for 3 hours. Then, the three-necked flask is placed in a thermostatic magnetic stirrer with the temperature set to 80°C and the speed set to 220 rpm. Hexamethylene diisocyanate is dissolved in 5 mL of N,N-dimethylformamide and added to the three-necked flask. Next, dibutyltin dilaurate is added as a catalyst, and the reaction is carried out for 4 hours. During the reaction, an additional 40 mL of N,N-dimethylformamide is added to reduce the viscosity of the reaction, thus obtaining the prepolymer PEG-HDI.

[0059] Step 2: Set the temperature of the thermostatic magnetic stirrer to 65℃ and maintain the speed at 220 rpm. Dissolve dimethylglyoxime and anhydrous zinc chloride in 5 mL of N,N-dimethylformamide and add them to the three-necked flask containing PEG-HDI from Step 1. Continue the reaction for 3 hours. Then, dissolve pentaerythritol in 5 mL of N,N-dimethylformamide and add it to the three-necked flask. Continue stirring for 20 minutes to obtain a polyurethane solution.

[0060] Step 3: Pour the polyurethane solution obtained in Step 2 into a polytetrafluoroethylene mold and dry it in a 60℃ oven for 24 hours to obtain a reprocessable and self-healing polyurethane solid-solid phase change material, namely Zn. 2+ -OUPCMs.

[0061] Example 3

[0062] A reprocessable and self-healing polyurethane solid-solid phase change material is prepared from the following raw materials: polyethylene glycol (PEG, Mn = 4000 g / mol, 16 g, 4 moles), hexamethylene diisocyanate (HDI, 1.3039 g, 7.6 moles), dimethylglyoxime (DMG, 0.2323 g, 2 moles), anhydrous nickel chloride (NiCl2, 0.1296 g, 1 mole), pentaerythritol (PTOL, 0.1090 g, 0.8 moles), dibutyltin dilaurate (DBTDL, 0.18 g, 1 wt%), and N,N-dimethylformamide (DMF, 60 mL).

[0063] The preparation method of the reprocessable and self-healing polyurethane solid-solid phase change material as described above includes the following steps:

[0064] Step 1: Under an argon atmosphere, polyethylene glycol is added to a three-necked flask and dried in a vacuum oven at 110°C for 3 hours. Then, the three-necked flask is placed in a thermostatic magnetic stirrer with the temperature set to 80°C and the speed set to 220 rpm. Hexamethylene diisocyanate is dissolved in 5 mL of N,N-dimethylformamide and added to the three-necked flask. Next, dibutyltin dilaurate is added as a catalyst, and the reaction is carried out for 4 hours. During the reaction, an additional 40 mL of N,N-dimethylformamide is added to reduce the viscosity of the reaction, thus obtaining the prepolymer PEG-HDI.

[0065] Step 2: Set the temperature of the thermostatic magnetic stirrer to 65℃ and maintain the speed at 220 rpm. Dissolve dimethylglyoxime and anhydrous nickel chloride in 5 mL of N,N-dimethylformamide and add them to the three-necked flask containing PEG-HDI from Step 1. Continue the reaction for 3 hours. Then, dissolve pentaerythritol in 5 mL of N,N-dimethylformamide and add it to the three-necked flask. Continue stirring for 20 minutes to obtain a polyurethane solution.

[0066] Step 3: Pour the polyurethane solution obtained in Step 2 into a polytetrafluoroethylene mold and dry it in a 60℃ oven for 24 hours to obtain a reprocessable and self-healing polyurethane solid-solid phase change material, namely Ni. 2+ -OUPCMs.

[0067] Comparative Example 1

[0068] In this comparative example, anhydrous copper chloride was not used in the raw materials. Butanedione oxime was replaced with 1,4-butanediol (BDO). The other raw materials, dosages, and preparation methods were the same as in Example 1. Polyurethane solid-solid phase change materials, namely BDO-PCMs, were prepared.

[0069] The BDO-PCMs sample was cut into small pieces and then hot-pressed at 120℃ and 10MPa for 20 minutes. Figure 12 As shown, BDO-PCMs without the addition of dimethylglyoxime and metal compounds lack oxime-urethane bonds and metal coordination bonds. Under the influence of hydrogen bonds alone, they cannot form a complete film and have many cracks, thus lacking reprocessability.

[0070] Example 4

[0071] In this embodiment, step two is replaced by: adjusting the temperature of the constant temperature magnetic stirrer to 65°C and maintaining the rotation speed at 220 rpm; dissolving dimethylglyoxime and anhydrous copper chloride (CuCl2, 0.0941 g, 0.7 mol) in 5 mL of N,N-dimethylformamide and adding them to the three-necked flask containing PEG-HDI from step one; continuing the reaction for 3 h; then radio frequency treatment for 10 min using an RF device; then dissolving anhydrous ferrous chloride (FeCl2, 0.038 g, 0.3 mol) in 5 mL of N,N-dimethylformamide and adding it to the three-necked flask; continuing the reaction for 1 h; then dissolving pentaerythritol in 5 mL of N,N-dimethylformamide and adding it to the three-necked flask; and continuing stirring for 20 min to obtain a polyurethane solution; wherein the power of the RF treatment is 6 kW, the frequency is 27 MHz, and the electrode spacing is 20 cm; the remaining raw materials, amounts, and methods are the same as in Example 1.

[0072] This embodiment employs a two-stage coordination reaction, first reacting with Cu... 2+ Coordination occurs, followed by interaction with Fe. 2+ Coordination occurs between the two metal ions, which exhibit synergistic effects. Furthermore, radiofrequency treatment of the reaction system between the two coordination stages promotes the formation of dynamic metal-coordinate bonds, facilitating the exchange reaction of oxime and coordinate bonds, thus further improving its self-healing effect and enhancing its mechanical properties. The polyurethane solid-solid phase change material prepared in this embodiment has a tensile strength of 15.36 MPa, superior to the 14.08 MPa of Example 1, and a self-healing efficiency of 95.52%, superior to the 91.34% of Example 1.

[0073] Example 5

[0074] In this embodiment, step two is replaced by: adjusting the temperature of the constant temperature magnetic stirrer to 65°C and maintaining the rotation speed at 220 rpm; dissolving dimethylglyoxime and anhydrous copper chloride (CuCl2, 0.0941 g, 0.7 mol) in 5 mL of N,N-dimethylformamide and adding them to the three-necked flask containing PEG-HDI from step one; continuing the reaction for 3 h; then dissolving anhydrous ferrous chloride (FeCl2, 0.038 g, 0.3 mol) in 5 mL of N,N-dimethylformamide and adding it to the three-necked flask; continuing the reaction for 1 h; then dissolving pentaerythritol in 5 mL of N,N-dimethylformamide and adding it to the three-necked flask; and continuing stirring for 20 min to obtain a polyurethane solution; the remaining raw materials, amounts, and methods are the same as in Example 1.

[0075] The polyurethane solid-solid phase change material prepared in this embodiment has a tensile strength of 14.72 MPa and a self-healing efficiency of 93.67%, both of which are superior to those in Example 1.

[0076] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for the preparation of a reworkable and self-healing polyurethane solid-solid phase change material, characterized in that, The method comprises the following steps: Step one, under argon or nitrogen atmosphere, polyethylene glycol is added into a reactor for water removal treatment, then diisocyanate is dissolved in a solvent and added into the reactor under the condition of 80-85℃ and stirring speed of 200-250rpm, followed by adding a catalyst, and the reaction is carried out for 3-5h to obtain a prepolymer; Step two, adjusting the temperature, dissolving dimethylglyoxime and anhydrous cupric chloride in a solvent respectively and adding them into the reactor containing the prepolymer in step one, continuing the reaction for 2-4h, then using a radio frequency device for radio frequency treatment for 5-20min, dissolving anhydrous ferrous chloride in a solvent and adding it into the reactor, continuing the reaction for 1-2h, then dissolving pentaerythritol in a solvent and adding it into the reactor, continuing the stirring for 10-30min to obtain a polyurethane solution; wherein the power of the radio frequency treatment is 5-8kW, the frequency is 27MHz, and the electrode plate spacing is 10-30cm; the molar ratio of anhydrous cupric chloride to anhydrous ferrous chloride is 0.5-0.9:0.1-0.5; the total molar of anhydrous cupric chloride and anhydrous ferrous chloride to the molar of dimethylglyoxime is 1:1-4; Step three, pouring the polyurethane solution obtained in step two into a polytetrafluoroethylene mold, and drying in an oven to obtain a reworkable and self-repairing polyurethane solid-solid phase change material.

2. A process for the preparation of a reworkable and self-healing polyurethane solid-solid phase change material according to claim 1, characterized in that, The molar ratio of the polyethylene glycol, diisocyanate, dimethylglyoxime and pentaerythritol is 3-5:7-8:1-3:0.5-1.

3. A process for the preparation of a reworkable and self-healing polyurethane solid-solid phase change material as claimed in claim 1, wherein, The polyethylene glycol is one or more of polyethylene glycol 2000, polyethylene glycol 4000, polyethylene glycol 6000, polyethylene glycol 8000 and polyethylene glycol 10000.

4. A process for the preparation of a reworkable and self-healing polyurethane solid-solid phase change material as claimed in claim 1, wherein, The diisocyanate is one or more of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate and diphenylmethane diisocyanate.

5. A process for the preparation of a reworkable and self-healing polyurethane solid-solid phase change material as claimed in claim 1, wherein, The catalyst is dibutyltin dilaurate; and the solvent is N,N-dimethylformamide, tetrahydrofuran or dimethyl sulfoxide.

6. A process for the preparation of a reworkable and self-healing polyurethane solid-solid phase change material as claimed in claim 1, wherein, In step one, the water removal treatment is vacuum drying at 100-120℃ for 2-4h; the mass-volume ratio of diisocyanate to solvent is 1-2g:4-10mL; and the catalyst is used in an amount of 0.5-2% of the total mass of polyethylene glycol and diisocyanate.

7. A process for the preparation of a reworkable and self-healing polyurethane solid-solid phase change material as claimed in claim 1, wherein, In step two, the temperature is adjusted to 60-70℃; the mass-volume ratio of dimethylglyoxime to solvent is 0.1-1g:4-10mL; the mass-volume ratio of the total mass of anhydrous cupric chloride and anhydrous ferrous chloride to solvent is 0.1-1g:4-10mL; and the mass-volume ratio of pentaerythritol to solvent is 0.1-1g:4-10mL.

8. A process for the preparation of a reworkable and self-healing polyurethane solid-solid phase change material as claimed in claim 1, wherein, In step three, the drying temperature is 50-80℃, and the drying time is 20-30h.

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