Preparation method of bio-based degradable polyethylene glycol flexible solid-solid phase change material

Abstract

The invention discloses a preparation method of a bio-based degradable polyethylene glycol flexible solid-solid phase change material, which is characterized in that a green and efficient dynamic covalent cross-linking strategy is adopted, firstly succinic anhydride modified polyethylene glycol (CPEG) is endowed with terminal carboxylation, and the terminal carboxylation is used as a phase change component and a cross-linking agent; bio-based epoxidized soybean oil (ESO) is used as a packaging matrix, 3, 3 '-dithiodipropionic acid (DPA) is used as a co-crosslinking agent to co-crosslink the ESO with CPEG, epoxy and carboxyl groups react to construct a'rigid-flexible' dual-network structure with dynamic hydroxyl ester bonds and disulfide bonds, and finally, the flexible solid-solid phase change material (CPEG / S-S / ESO) is prepared through high-temperature curing and hot press molding. According to the system, a polyethylene glycol (PEG) phase-change component is introduced into a cross-linked network, reversible cross-linking and structure stabilization of the phase-change material are achieved at the same time, dynamic hydroxyl ester bonds and disulfide bonds endow the PEG phase-change material with the excellent degradable characteristic, controllable degradation can be achieved in multiple solvents, and the system is suitable for industrial production. And meanwhile, the characteristics of high mechanical strength, high phase change enthalpy, shape stability and reprocessability are kept. The preparation method disclosed by the invention provides a new thought for developing a high-performance and sustainable solid-solid phase change material.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high polymer material preparation, and particularly relates to a preparation method of a bio-based degradable polyethylene glycol flexible solid-solid phase change material. BACKGROUND

[0002] With the rapid development of artificial intelligence, computer and other technologies, electronic devices are evolving towards miniaturization, high integration and ultra-high power density, and the heat dissipation problem of electronic devices is becoming increasingly severe. Traditional heat dissipation technologies such as air cooling, liquid cooling or heat pipe can cope with conventional heat load, but their defects such as large volume, response lag and high energy consumption make it difficult to meet the needs of portable electronic devices or high-precision packaging scenarios. Therefore, developing new heat management materials that have high efficient heat absorption and release, small size and maintain small temperature fluctuations has become a technical bottleneck that the electronic industry needs to overcome.

[0003] Phase change materials (PCMs) have been widely studied and applied in thermal management due to their latent heat absorption characteristics during phase transition. However, traditional solid-liquid PCMs have issues such as liquid leakage and poor thermal cycling stability, which severely limit their application in precision electronic devices. In contrast, solid-solid PCMs achieve thermal energy storage and release through chemical crosslinking, with advantages such as no leakage and good thermal cycling stability. However, they still face challenges such as poor mechanical strength, non-recyclability, poor flexibility, and a lack of research on degradable PCMs. Polyethylene glycol (PEG) is considered an ideal solid-solid PCM due to its high phase change enthalpy, adjustable wide temperature range, and biocompatibility. Current research on PEG-based solid-solid PCMs mainly involves chemical grafting modification of PEG and synthesis of crosslinked copolymers. PEG serves as the phase change component and soft segment, and a polymer backbone or hard segment is introduced into the molecular chain as structural support. Among them, polyurethane series solid-solid PCMs are the most common. Wang Ganlu et al., ACS Applied Materials & Interfaces, 2024, 16(51): 70149-70159, developed a wood-based composite PCM modified by polypyrrole (PEG(EP)@PPy / DW) with a high PEG content of 64.58% and a melting enthalpy of 102 J / g, and exhibited excellent shape stability, maintaining its integrity even at temperatures up to 200℃. Chen Changzhong et al., Solar Energy, 2011, 85(11): 2679-2685, synthesized a modified PEG10000 / poly(glycidyl methacrylate) (PGMA) crosslinked copolymer through ring-opening crosslinking reaction, which maintained excellent shape stability even when the temperature rose above 100℃. However, traditional crosslinking systems often form irreversible covalent networks, making the materials difficult to recycle. Physical blending can easily cause phase separation, reducing the cycling stability. How to synergistically optimize the mechanical properties and dynamic reversibility of PCMs still faces serious challenges.

[0004] Chinese patent CN119735831A discloses a preparation method of a polyethylene glycol solid-solid phase change material, a solidification system composed of a polyethylene glycol-poly(2-vinyl) glycol copolymer and a multifunctional mercaptan compound, which can improve the balance between the heat storage capacity and the mechanical properties of the polyethylene glycol solid-solid phase change material, and realize a polymer network with high crosslinking density and good thermal stability. Chinese patent CN110628033B discloses a polyimide grafted polyethylene glycol composite solid-solid phase change material and a preparation method thereof, which forms a crosslinked network structure through the interaction of polyethylene glycol, polyimide precursor and intermolecular functional groups and hydrogen bonds of graphene oxide, and forms a stable crosslinked skeleton structure through further thermal crosslinking of the polyimide precursor under high temperature and inert atmosphere. The above preparation method of the polyethylene glycol solid-solid phase change material is relatively complex, the synthesis or modification method is cumbersome, high temperature inert gas is used, and it is not degradable and recyclable. Therefore, it is still a challenge to develop a flexible polyethylene glycol solid-solid phase change material with excellent comprehensive performance. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of a biobased degradable polyethylene glycol flexible solid-solid phase change material, which overcomes the shortcomings of the prior art. The feature is to use succinic anhydride modified PEG (CPEG) to endow it with carboxyl groups, to use it as a phase change component, and to co-solidify biobased epoxy soybean oil (ESO) with 3,3'-dithiodipropionic acid (DPA) to occur ring-opening esterification reaction, design and construct a "rigid and flexible" dynamic hydroxyl ester bond and disulfide bond double dynamic covalent network, and prepare a PEG-based flexible solid-solid phase change material (CPEG / S-S / ESO). The dynamic hydroxyl ester bond and disulfide bond endow the phase change material with high efficient reprocessing ability and dynamic recycling characteristics, and realize degradation and recycling in various solvents. At the same time, the double crosslinked network endows the phase change material with high phase change enthalpy, excellent thermal cycle durability, mechanical strength and shape stability. The flexible solid-solid phase change material prepared by the present application has high phase change enthalpy, recyclability, mechanical flexibility and degradation characteristics, and can be used in the field of thermal management.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: Wherein, the raw material fraction is mass fraction unless otherwise specified.

[0007] A preparation method of a biobased degradable polyethylene glycol flexible solid-solid phase change material, mainly composed of the following components, in mass fraction: Polyethylene glycol 100 parts Succinic anhydride 1-10 parts Epoxy soybean oil 20-50 parts 3,3'-dithiodipropionic acid 2-20 parts Triethylamine 0.2-1 part Catalyst 0.3-1 parts The polyethylene glycol has a molecular weight of 1000-10000. The catalyst is any one of 4-dimethylaminopyridine, 2-methylpyridine, sulfurous acid chloride, and 2-aminopyridine.

[0008] A preparation method of a biobased degradable polyethylene glycol flexible solid-solid phase change material, characterized by comprising the following steps: S1: preparation of carboxyl-terminated polyethylene glycol (CPEG) 100 parts of polyethylene glycol (PEG) with a molecular weight of 1000-10000 is added to 300-500 parts of dichloromethane, stirred at room temperature until dissolved, 1-10 parts of succinic anhydride (SA) is added under anhydrous conditions, and esterification reaction is carried out at 70-90°C under the action of 0.3-1 parts of catalyst for 2-6 h, then placed in a 50°C oven for 2 h after the reaction is completed, the volatile organic solvent is removed, and then cooled at room temperature to obtain carboxyl-terminated PEG (CPEG); S2: preparation of polyethylene glycol flexible solid-solid phase change material (CPEG / S-S / ESO) The CPEG prepared above is added to 150 parts of an ethanol solvent, ultrasonically stirred at room temperature to obtain a uniform CPEG solution, then 2-20 parts of 3,3'-dithiodipropionic acid (DPA) is added and dissolved, followed by addition of 20-50 parts of epoxy soybean oil (ESO) and 0.2-1 parts of triethylamine, and then the mixture is stirred at 90°C for 2-8 h to promote ring-opening reaction of the epoxy group and the carboxyl group, thereby obtaining a reaction precursor, which is then placed at rest at 130-150°C for 0.5-3 h, and then hot-pressed at 160-200°C and 5-10 MPa for 5-30 min to prepare the flexible PEG solid-solid phase change material (CPEG / S-S / ESO).

[0009] The present application has the following advantages: To solve the leakage problem of solid-liquid phase change composites in application, a solid-solid phase change material based on a double dynamic covalent network is innovatively designed. Succinic anhydride is used to modify PEG to endow it with carboxyl groups, and the modified PEG is used as a phase change component and a crosslinking agent, and is co-solidified with 3,3'-dithiodipropionic acid and biobased epoxy soybean oil to design and construct a "rigid-flexible" dynamic hydroxyl ester bond and disulfide bond double dynamic covalent structure. The dynamic hydroxyl ester bond and disulfide bond endow the PEG phase change material with excellent mechanical strength, degradability and reworkability, and also endow the phase change material with high phase change enthalpy, no leakage under high temperature heating, stable enthalpy value after thermal cycling, and controllable degradation in various solvents, realizing rework and recycling.

[0010] A bio-based epoxy soybean oil is used as a matrix, a carboxylated PEG is used as a phase change component and a crosslinking agent, a dynamic network structure is regulated, the high-temperature shape stability of the PEG is improved, and the PEG is endowed with controllable degradation, mechanical flexibility and reprocessing characteristics, and the comprehensive performance has a significant advantage in the field of solid-solid phase change materials. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 Reaction structure diagram of the polyethylene glycol flexible solid-solid phase change material.

[0012] Figure 2 Mechanical flexibility and shape stability display of the polyethylene glycol flexible solid-solid phase change material.

[0013] Figure 3 Reprocessing and degradation performance of the polyethylene glycol flexible solid-solid phase change material. DETAILED DESCRIPTION

[0014] The application will be further described below through specific examples, and it should be noted that the examples are only used to further illustrate the application and cannot be understood as limiting the protection scope of the application. Those skilled in the art can make non-essential improvements and adjustments to the application according to the above content of the application. Example 1

[0015] 100 parts of polyethylene glycol (PEG) with a molecular weight of 1000 were added to 500 parts of dichloromethane, stirred at room temperature until dissolved, 10 parts of succinic anhydride (SA) were added under anhydrous conditions, and esterification reaction was carried out at 90°C for 5 h under the catalysis of 1 part of 2-aminopyridine, and then the reaction mixture was placed in a 50°C oven for 2 h, the volatile organic solvent was removed, and then the mixture was cooled at room temperature to obtain carboxyl-terminated PEG (CPEG).

[0016] The CPEG prepared above was added to 150 parts of an ethanol solvent, and a uniform CPEG solution was obtained by ultrasonicating and stirring at room temperature, then 18 parts of 3,3'-dithiodipropionic acid (DPA) were added and dissolved, then 50 parts of epoxy soybean oil (ESO) and 1 part of triethylamine were added, and the mixture was stirred at 90°C for 6 h to promote the ring-opening reaction of the epoxy groups and the carboxyl groups, thereby obtaining a reaction precursor, and then the reaction precursor was placed at 135°C for 3 h, and then the mixture was hot-pressed at 160°C and 6 MPa for 10 min to prepare a flexible PEG solid-solid phase change material (CPEG / S-S / ESO). Test results show that the phase change material has a melting enthalpy of 98 J / g, a tensile strength of 2.52 MPa, a mechanical strength recovery rate of 89% after reprocessing 3 times, no leakage after heating at 150°C for 3 h, and complete degradation at room temperature without any catalyst in ethanol, dimethyl sulfoxide (DMSO), strong acid (HCl, H2SO4) and strong base (NaOH). Example 2

[0017] 100 parts of polyethylene glycol (PEG) with a molecular weight of 4000 were added to 400 parts of dichloromethane, stirred at room temperature until dissolved, 6 parts of succinic anhydride (SA) were added under anhydrous conditions, and esterification was carried out at 80°C for 4 h under the catalysis of 0.6 parts of 2-methylpyridine, and then the reaction mixture was placed in an oven at 50°C for 2 h after the reaction was completed, the organic solvent was volatilized, and then cooled at room temperature to obtain carboxyl-terminated PEG (CPEG); The CPEG prepared above was added to 150 parts of an ethanol solvent, and a uniform CPEG solution was obtained by ultrasonicating and stirring at room temperature, followed by adding 150 parts of 3,3'-dithiodipropionic acid (DPA) to dissolve it completely, then adding 40 parts of epoxidized soybean oil (ESO) and 1 part of triethylamine, and stirring at 90°C for 6 h to promote the ring-opening reaction of the epoxy groups with the carboxyl groups, thereby obtaining a reaction precursor. After being left to react at 140°C for 2.5 h, the flexible PEG solid-solid phase change material (CPEG / S-S / ESO) was prepared by hot-pressing at 170°C and 8 MPa for 12 min. The melting enthalpy of the phase change material was 108 J / g, the tensile strength was 3.66 MPa, the mechanical strength recovery rate was 91% after 3 times of repeated processing, there was no leakage after being heated at 150°C for 3 h, and it was completely degraded at room temperature without any catalyst in ethanol, dimethyl sulfoxide (DMSO), strong acid (HCl, H2SO4), and strong base (NaOH). Example 3

[0018] 100 parts of polyethylene glycol (PEG) with a molecular weight of 6000 were added to 350 parts of dichloromethane, stirred at room temperature until dissolved, 5 parts of succinic anhydride (SA) were added under anhydrous conditions, and esterification was carried out at 90°C for 6 h under the catalysis of 0.4 parts of 4-dimethylaminopyridine, and then the reaction mixture was placed in an oven at 50°C for 2 h after the reaction was completed, the organic solvent was volatilized, and then cooled at room temperature to obtain carboxyl-terminated PEG (CPEG); The CPEG prepared above was added to 150 parts of ethanol solvent, and a uniform CPEG solution was obtained by ultrasonicating and stirring at room temperature. Then, 10 parts of 3,3'-dithiodipropionic acid (DPA) was fully dissolved, and then 40 parts of epoxy soybean oil (ESO) and 0.8 parts of triethylamine were added. The mixture was stirred at 90°C for 6 h to promote the ring-opening reaction of the epoxy groups and the carboxyl groups, and a reaction precursor was obtained. After standing at 150°C for 3 h, the flexible PEG solid-solid phase change material (CPEG / S-S / ESO) was prepared by hot pressing at 180°C and 10 MPa for 10 min. The test results show that the melting enthalpy of the phase change material is 111 J / g, the tensile strength is 5.92 MPa, the mechanical strength recovery rate is 92% after 3 times of repeated processing, there is no leakage after heating at 150°C for 3 h, and the material is completely degraded at room temperature without any catalyst in ethanol, dimethyl sulfoxide (DMSO), strong acid (HCl and H2SO4), and strong base (NaOH). Example 4

[0019] 100 parts of polyethylene glycol (PEG) with a molecular weight of 6000 were added to 350 parts of dichloromethane, and the mixture was stirred at room temperature until the PEG was dissolved. Then, 5 parts of succinic anhydride (SA) was added under anhydrous conditions, and the mixture was stirred at 90°C for 6 h to perform esterification under the catalysis of 0.4 parts of 4-dimethylaminopyridine. After the reaction was completed, the mixture was placed in an oven at 50°C for 2 h to volatilize the organic solvent, and then the mixture was cooled at room temperature to obtain carboxyl-terminated PEG (CPEG). The CPEG prepared above was added to 150 parts of ethanol solvent, and a uniform CPEG solution was obtained by ultrasonicating and stirring at room temperature. Then, 10 parts of 3,3'-dithiodipropionic acid (DPA) was fully dissolved, and then 30 parts of epoxy soybean oil (ESO) and 0.6 parts of triethylamine were added. The mixture was stirred at 90°C for 6 h to promote the ring-opening reaction of the epoxy groups and the carboxyl groups, and a reaction precursor was obtained. After standing at 150°C for 3 h, the flexible PEG solid-solid phase change material (CPEG / S-S / ESO) was prepared by hot pressing at 160°C and 10 MPa for 15 min. The test results show that the melting enthalpy of the phase change material is 108 J / g, the tensile strength is 4.59 MPa, the mechanical strength recovery rate is 90% after 3 times of repeated processing, there is no leakage after heating at 150°C for 3 h, and the material is completely degraded at room temperature without any catalyst in ethanol, dimethyl sulfoxide (DMSO), strong acid (HCl and H2SO4), and strong base (NaOH). Example 5

[0020] 100 parts of polyethylene glycol (PEG) with a molecular weight of 10000 was added to 300 parts of dichloromethane, stirred at room temperature until dissolved, 14 parts of succinic anhydride (SA) was added under anhydrous conditions, and esterification was carried out at 80°C for 5 h under the catalysis of 0.3 parts of sulfuric chloride, after the reaction was completed, it was placed in an oven at 50°C for 2 h, the organic solvent was volatilized, then cooled at room temperature to obtain carboxyl-terminated PEG (CPEG); The CPEG prepared above was added to 150 parts of ethanol solvent, ultrasonic and stirring at room temperature to obtain a uniform CPEG solution, then 6 parts of 3,3'-dithiodipropionic acid (DPA) was added to dissolve completely, then 20 parts of epoxy soybean oil (ESO) and 0.4 parts of triethylamine were added, and the open ring reaction of epoxy groups and carboxyl groups was promoted by stirring at 90°C for 3 h to obtain a reaction precursor, after standing at 140°C for 2 h, the flexible PEG solid-solid phase change material (CPEG / S-S / ESO) was prepared by hot pressing at 170°C and 8 MPa for 20 min. The test showed that the melting enthalpy of the phase change material was 113 J / g, the tensile strength was 5.68 MPa, the mechanical strength recovery rate was 88% after 3 times of repeated processing, there was no leakage after heating at 150°C for 3 h, and it could be completely degraded at room temperature without any catalyst in ethanol, dimethyl sulfoxide (DMSO), strong acid (HCl, H2SO4) and strong base (NaOH).

[0021] Comparative Example 1 100 parts of polyethylene glycol (PEG) with a molecular weight of 6000 was added to 350 parts of dichloromethane, stirred at room temperature until dissolved, then directly placed in an oven at 50°C for 2 h, the organic solvent was volatilized, then cooled at room temperature; The PEG obtained above was added to 150 parts of ethanol solvent, ultrasonic and stirring at room temperature to obtain a uniform PEG solution, then 10 parts of 3,3'-dithiodipropionic acid (DPA) was added to dissolve completely, then 40 parts of epoxy soybean oil (ESO) and 0.8 parts of triethylamine were added, and the open ring reaction of epoxy groups and carboxyl groups was promoted by stirring at 90°C for 6 h to obtain a reaction precursor, after standing at 150°C for 3 h, the PEG phase change material was prepared by hot pressing at 180°C and 10 MPa for 10 min. The test showed that the melting enthalpy of the phase change material was 116 J / g, the tensile strength was 3.37 MPa, the mechanical strength recovery rate was 84% after 3 times of repeated processing, leakage occurred after heating at 150°C for 0.5 h, and it could be degraded at room temperature without any catalyst in ethanol, dimethyl sulfoxide (DMSO), strong acid (HCl, H2SO4) and strong base (NaOH), the degradation process was slow and PEG precipitation occurred in part of the solvents.

[0022] In summary, the embodiment of the present application changes the reaction conditions of carboxylation of polyethylene glycol, dynamic crosslinking reaction conditions and curing reaction conditions, regulates the double dynamic crosslinking network, and gives the phase change material high mechanical strength, high phase change enthalpy, reprocessing and degradable characteristics. Through Example 3 and Comparative Example 1, it can be seen that after carboxylation of polyethylene glycol, it can participate in the crosslinking reaction of epoxy soybean oil, introduce it into the crosslinking network, realize the preparation of solid-solid phase change material, and obviously improve the high-temperature shape stability; on the contrary, the polyethylene glycol which is not carboxylated cannot participate in the crosslinking reaction, and the shape stability of the prepared phase change material is poor, which is a non-solid-solid phase change material.

[0023] The above embodiments have described the specific content of the present application in detail, but the present application is not limited to the described embodiments, and those skilled in the art can make equivalent replacements, which should be covered within the protection scope of the present application.

Claims

1. A method for the preparation of a bio-based degradable polyethylene glycol flexible solid-solid phase change material, characterized in that The phase change material is mainly composed of the following components, by mass fraction: Polyethylene glycol 100 parts Butanedioic anhydride 1-10 parts Epoxy soybean oil 20-50 parts 3,3'-dithiodipropionic acid 2-20 parts Triethylamine 0.2-1 part Catalyst 0.3-1 part Among them, the molecular weight of the polyethylene glycol is 1000-10000 g / mol; The catalyst is any one of 4-dimethylaminopyridine, 2-methylpyridine, sulfurous acid chloride, 2-aminopyridine.

2. A method for the preparation of a bio-based degradable polyethylene glycol flexible solid-solid phase change material, characterized by, Comprising the following steps: S1: Preparation of carboxyl-terminated polyethylene glycol CPEG 100 parts of polyethylene glycol PEG with a molecular weight of 1000-10000 is added to 300-500 parts of dichloromethane, stirred at room temperature until dissolved, 1-10 parts of succinic anhydride SA is added under anhydrous conditions, and esterification reaction is carried out at 70-90°C under the action of 0.3-1 parts of catalyst for 2-6 h, after the reaction is completed, it is placed in a 50°C oven for 2 h, the organic solvent is volatilized, then it is cooled at room temperature, and carboxyl-terminated PEG (CPEG) is obtained; S2: Preparation of polyethylene glycol flexible solid-solid phase change material CPEG / S-S / ESO The CPEG prepared above is added to 150 parts of ethanol solvent, ultrasonic and stirring at room temperature to obtain a uniform CPEG solution, then 2-20 parts of 3,3'-dithiodipropionic acid DPA is added and dissolved, then 20-50 parts of epoxy soybean oil ESO and 0.2-1 parts of triethylamine are added, and the mixture is stirred at 90°C for 2-8 h to promote the ring-opening reaction of the epoxy group and the carboxyl group, thereby obtaining a reaction precursor, after standing at 130-150°C for 0.5-3 h, the flexible PEG solid-solid phase change material CPEG / S-S / ESO is prepared by hot pressing at 160-200°C and 5-10 MPa for 5-30 min.

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