Hyperbranched polyimide embedding material as well as preparation method and application thereof
By preparing porous hyperbranched polyimide embedding materials through supercritical carbon dioxide fluid processing, the problem of solvent residue in traditional embedding materials under extreme conditions was solved, achieving stable encapsulation and performance improvement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JINGGANGSHAN UNIVERSITY
- Filing Date
- 2026-03-09
- Publication Date
- 2026-05-08
AI Technical Summary
Traditional embedding materials are difficult to meet the requirements for long-term use under extreme conditions such as high temperature, high mechanical stress or strong chemical corrosion. Furthermore, the solution blending-evaporation method for preparing hyperbranched polyimide materials has solvent residue problems, which affect its performance in combination with other materials.
A hyperbranched polyimide solution with active end groups was treated with supercritical carbon dioxide fluid and then used to embed functional materials. By filtration, drying and control of reaction pressure, a porous hyperbranched polyimide embedding material was prepared. The solvent was removed by utilizing the dissolving and extracting capabilities of SC-CO2 to form a stable embedding system.
Stable encapsulation of hyperbranched polyimide embedding materials with no solvent residue was achieved, improving the mechanical properties of its composites with other materials and meeting the requirements for long-term use under extreme conditions.
Smart Images
Figure CN121991397A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of high-performance polymer materials and advanced micro-encapsulation technology, and relates to a hyperbranched polyimide embedding material, its preparation method, and its application. Specifically, it relates to a method for preparing hyperbranched polyimide embedding materials using supercritical carbon dioxide fluid, and its application. Background Technology
[0002] Encapsulation technology, also known as microencapsulation technology, is a technology that protects functional materials (such as catalysts, dyes, phase change materials, etc.) from environmental factors (such as high temperature, oxygen, humidity). This technology is urgently needed in fields such as electronics, aerospace, military industry and high-end manufacturing.
[0003] However, traditional embedding materials, such as ordinary linear polymers or the aforementioned hyperbranched polyesters, often fail to meet the requirements for long-term use under extreme conditions such as temperatures above 200°C, high mechanical stress, or strong chemical corrosion in terms of heat resistance and mechanical strength. Studies have found that hyperbranched polyimide (HBPI) can meet these requirements, making it an ideal candidate material for embedding carriers due to its good temperature resistance and processability. However, the commonly used solution blending-evaporation method for preparing HBPI not only suffers from significant solvent residue problems but also prevents the protective functional substances from being fully encapsulated by the HBPI. This affects the application performance of HBPI embedding materials prepared by this method in combination with other materials, such as the mechanical properties of the final composite material. Therefore, it is urgent to explore a method for preparing hyperbranched polyimide embedding materials. Summary of the Invention
[0004] To address the shortcomings of the prior art, the present invention aims to provide a hyperbranched polyimide embedding material, its preparation method, and its application. This preparation method does not have a significant solvent residue problem, enabling the hyperbranched polyimide embedding material to achieve stable encapsulation without affecting its performance in composites with other materials.
[0005] To solve the above-mentioned technical problems, the present invention provides a method for preparing hyperbranched polyimide embedding material, comprising the following steps: dropping a hyperbranched polyimide solution with active end groups into an embedding functional material, and then filtering and drying it to obtain the embedding powder; The embedded powder was placed in a supercritical carbon dioxide fluid at a temperature of 31℃~80℃ and a pressure of 8MPa~30MPa for 0.5h~6h to obtain a porous structure. The reaction pressure was then adjusted to atmospheric pressure at a depressurization rate of 0.1MPa / min~2MPa / min and dried to obtain a hyperbranched polyimide embedded material. The hyperbranched polyimide with active end groups is at least one of the following: polyimide with hydroxyl end groups, polyimide with siloxane end groups, and polyimide with anhydride end groups.
[0006] Preferably, the hyperbranched polyimide solution with active end groups is prepared by dissolving hyperbranched polyimide with active end groups in an organic solvent. The amount of the organic solvent is such that the mass concentration of hyperbranched polyimide with active end groups in the resulting solution is 1% to 20% (i.e., the concentration of hyperbranched polyimide with active end groups in the solution is 1% to 20%), and the organic solvent is at least one of N,N-dimethylacetamide, N-methylpyrrolidone, or N,N-dimethylformamide.
[0007] The reason for setting the amount of organic solvent to be 1% to 20% of the mass concentration of hyperbranched polyimide with active end groups in the resulting solution is that if the amount of organic solvent is less than 1%, the concentration of the hyperbranched polyimide solution with active end groups will be too high, the viscosity will be too high, and the coating effect will be too poor.
[0008] Preferably, the mass percentage of hyperbranched polyimide with active end groups to the embedded functional material in the solution of hyperbranched polyimide with active end groups is 0.08% to 1.5%.
[0009] The mass percentage of hyperbranched polyimide with active end groups to the encapsulated functional material in the solution of hyperbranched polyimide with active end groups is 1:0.08% to 1.5%. This is because a ratio that is too large or too small will affect the encapsulation effect. If the encapsulation is too thick, it cannot be effectively released; if it is too thin, the active material may be unstable when exposed to extreme environments.
[0010] Preferably, the supercritical carbon dioxide fluid is treated at a temperature of 35°C to 60°C, at a pressure of 10 MPa to 25 MPa, and for a duration of 1 hour to 4 hours.
[0011] Preferably, the treatment temperature of the embedded precursor in supercritical carbon dioxide fluid is 50℃~55℃, the treatment pressure is 15MPa~20MPa, and the treatment time is 3h~4h.
[0012] Preferably, the pressure reduction rate is 1 MPa / min, the drying temperature is 80℃~100℃, and the drying time is 2h~5h.
[0013] Preferably, the encapsulating functional material is one of a dye, a phase change material, a catalyst, or an antioxidant, wherein the antioxidant is at least one of antioxidant 245, antioxidant 1010, or antioxidant 1076; the phase change material is at least one of n-octadecane, n-tetracosane, n-eicosane, or oxidized polyethylene wax; the catalyst is at least one of iron(II,III) oxide, vanadium(II,III) oxide, or zinc(II) oxide; and the dye is at least one of iron(II,III) oxide, lead(II,III) chromate, or chromium(II,III) oxide.
[0014] This invention provides a method for preparing hyperbranched polyimide embedding materials.
[0015] Preferably, the specific surface area of the hyperbranched polyimide embedding material is 10 m² / g to 500 m² / g.
[0016] This invention provides the application of hyperbranched polyimide embedding materials as fillers or active ingredients in the preparation of composite films, functional coatings, drug delivery systems, or phase change energy storage products.
[0017] The present invention provides a composite material comprising a hyperbranched polyimide embedding material.
[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: In the preparation method provided in this invention, at least one of the following—polyimide with hydroxyl-terminated groups, polyimide with siloxane-terminated groups, and polyimide with anhydride-terminated groups—is selected as the active end group of the hyperbranched polyimide, and one of the following—an antioxidant, a phase change material, a catalyst, or a dye—is used as the raw material to prepare the embedded powder. The embedded powder is then treated with supercritical carbon dioxide (SC-CO2), because SC-CO2 has liquid-like density and solubility, as well as gas-like low viscosity and high diffusion coefficient. This effectively swells and plasticizes the hyperbranched polyimide, enhancing its molecular chain mobility without causing chemical degradation, and creating kinetic conditions for functional substances to enter its internal cavities. Meanwhile, SC-CO2 has a strong extraction ability for most organic solvents, and can remove solvents with almost no residue under mild conditions. Through its unique solubility and depressurization rate, it induces a rich microporous structure in hyperbranched polyimide (HBPI), thereby fixing functional substances and forming a stable encapsulation system, thus improving its mechanical properties as an encapsulation material when combined with other materials. Attached Figure Description
[0019] Figure 1 The images show the infrared spectra of hyperbranched polyimide-embedded zinc oxide before and after SC-CO2 treatment prepared in Example 3 and Comparative Example 1 of this invention. Figure 2The images show the BET diagrams of hyperbranched polyimide-embedded zinc oxide prepared in Example 3 and Comparative Example 1 of this invention before and after SC-CO2 treatment. Figure 3 The images show SEM images of hyperbranched polyimide-embedded zinc oxide prepared in Example 3 and Comparative Example 1 of the present invention. The left image is an SEM image of hyperbranched polyimide-embedded zinc oxide prepared in Example 3, and the right image is an SEM image of hyperbranched polyimide-embedded zinc oxide prepared in Comparative Example 1. Detailed Implementation
[0020] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.
[0021] It should be noted that when numerical ranges are involved in this invention, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in Examples 1 to 23, preferred embodiments are described in this invention to avoid redundancy. However, this invention is not limited to these, but can be implemented in other ways within the scope of the technical solutions defined in the appended claims. All raw materials, reagents, instruments, and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.
[0022] The following detailed description, in conjunction with embodiments of the present invention and accompanying drawings, provides a clear and complete illustration of the technical solutions in these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0023] Example 1 A method for preparing a hyperbranched polyimide embedding material, the specific steps of which are as follows: (1) Preparation of embedded powder 0.05 g of hyperbranched polyimide (OH-HBPI) with hydroxyl end groups was dissolved in 0.2 mL of N,N-dimethylacetamide DMAc to obtain a hyperbranched polyimide solution with hydroxyl end groups. Then, the hyperbranched polyimide solution with hydroxyl end groups was added dropwise to 5 g of antioxidant 1010, stirred evenly, washed with water and filtered, and dried under reduced pressure at 60 °C to obtain the encapsulated powder.
[0024] (2) Preparation of hyperbranched polyimide embedding materials The embedded powder was transferred to a supercritical carbon dioxide autoclave, sealed, and purged with liquid carbon dioxide. The autoclave was then heated to 75°C and pressurized to 10 MPa. This supercritical state was maintained at constant temperature and pressure for 2 hours, allowing the hyperbranched polyimide to form a porous structure with numerous pores. The supercritical carbon dioxide autoclave was then depressurized to atmospheric pressure at a rate of 1 MPa / min. The resulting porous structure was then transferred to a vacuum drying oven and dried at 80°C for 3 hours to obtain the hyperbranched polyimide embedded material.
[0025] Example 2 A method for preparing a hyperbranched polyimide embedding material, the specific steps of which are as follows: (1) Preparation of embedded powder 0.03 g of siloxane-terminated hyperbranched polyimide (Si-HBPI) was dissolved in 0.3 ml of N,N-methyleneformamide DMF to obtain a siloxane-terminated hyperbranched polyimide solution. Then, the hyperbranched polyimide solution with hydroxyl end groups was added dropwise to 2 g of n-octadecane, stirred evenly, washed with water and filtered, and dried under reduced pressure at 60 °C to obtain the embedded powder.
[0026] (2) Preparation of hyperbranched polyimide embedding materials The embedded powder was transferred to a supercritical carbon dioxide autoclave, sealed, and then purged with liquid carbon dioxide. The autoclave was then heated to 80°C and pressurized to 8 MPa, and treated under these supercritical conditions for 3 hours. This process caused the hyperbranched polyimide to form a porous structure with numerous pores. The supercritical carbon dioxide autoclave was then depressurized to atmospheric pressure at 0.5 MPa / min, and the resulting porous product was transferred to a vacuum drying oven and dried at 85°C for 4 hours to obtain the hyperbranched polyimide embedded material.
[0027] Example 3 A method for preparing a hyperbranched polyimide embedding material, the specific steps of which are as follows: (1) Preparation of embedded powder 0.08 g of anhydride-terminated hyperbranched polyimide (Anhydride-HBPI) was dissolved in 0.8 ml of N-methylpyrrolidone (NMP) to obtain an anhydride-terminated hyperbranched polyimide solution. The anhydride-terminated hyperbranched polyimide solution was then added dropwise to 10 g of zinc oxide and stirred until homogeneous. After washing with water and filtration, the mixture was dried under reduced pressure at 60 °C to obtain the embedded powder.
[0028] (2) Preparation of hyperbranched polyimide embedding materials The embedded powder was placed in a supercritical carbon dioxide autoclave, sealed, and purged with liquid carbon dioxide. The autoclave was then heated to 80°C and pressurized to 10 MPa. Treatment under these supercritical conditions for 4 hours allowed the hyperbranched polyimide to form a porous structure with numerous pores. The supercritical carbon dioxide autoclave was then depressurized to atmospheric pressure at 2 MPa / min. The resulting porous product was then transferred to a vacuum drying oven and vacuum dried at 100°C for 2 hours to ensure complete solvent removal, yielding the hyperbranched polyimide embedded material.
[0029] Example 4 A method for preparing a hyperbranched polyimide embedding material, the specific steps of which are as follows: (1) Preparation of embedded powder 0.05 g of anhydride-terminated hyperbranched polyimide (Anhydride-HBPI) was dissolved in 0.8 ml of N-methylpyrrolidone (NMP) to obtain an anhydride-terminated hyperbranched polyimide solution. Then, the anhydride-terminated hyperbranched polyimide solution was added dropwise to 4 g of lead chromate, stirred evenly, washed with water and filtered, and dried under reduced pressure at 60 °C to obtain the embedded powder.
[0030] (2) Preparation of hyperbranched polyimide embedding materials The embedded powder was placed in a supercritical carbon dioxide autoclave, sealed, and purged with liquid carbon dioxide. The autoclave was then heated to 31°C and pressurized to 30 MPa. The mixture was treated under these supercritical conditions for 6 hours to form a porous product with numerous pores from the hyperbranched polyimide. The autoclave was then depressurized to atmospheric pressure at 0.1 MPa / min. The resulting porous product was then transferred to a vacuum drying oven and vacuum dried at 100°C for 5 hours to ensure complete solvent removal, yielding the hyperbranched polyimide embedded material.
[0031] Example 5 A method for preparing a hyperbranched polyimide embedding material, the specific steps of which are as follows: (1) Preparation of embedded powder 0.025 g of hydroxyl-terminated hyperbranched polyimide (OH-HBPI) and 0.025 g of siloxane-terminated polyimide were dissolved in 0.5 ml of N,N-dimethylacetamide (DMAc) to obtain a mixed solution of hydroxyl-terminated hyperbranched polyimide and siloxane-terminated polyimide. 5 g of antioxidant 1010 was added dropwise to the mixed solution and stirred until homogeneous. After washing with water and filtration, the mixture was dried under reduced pressure at 60 °C to obtain the encapsulated powder.
[0032] (2) Preparation of hyperbranched polyimide embedding materials The embedded powder was transferred to a supercritical carbon dioxide autoclave, sealed, and then liquid carbon dioxide was introduced. The autoclave was then heated to 60°C and pressurized to 8 MPa. This supercritical state was maintained at constant temperature and pressure for 0.5 hours, allowing the hyperbranched polyimide to form a porous product with numerous pores.
[0033] The supercritical carbon dioxide autoclave was depressurized to atmospheric pressure at a rate of 1 MPa / min, and the resulting porous product was then transferred to a vacuum drying oven and dried at 80°C for 3 hours to obtain hyperbranched polyimide embedding material.
[0034] Example 6 A method for preparing a hyperbranched polyimide embedding material, the specific steps of which are as follows: (1) Preparation of embedded powder 0.0025 g of hydroxyl-terminated hyperbranched polyimide (OH-HBPI) and 0.0025 g of anhydride-terminated polyimide were dissolved in 0.5 ml of N,N-dimethylacetamide DMAc to obtain a solution of hydroxyl-terminated hyperbranched polyimide and anhydride-terminated polyimide. The solution of hydroxyl-terminated hyperbranched polyimide and anhydride-terminated polyimide was added dropwise to 6.25 g of antioxidant 1010, stirred evenly, washed with water and filtered, and dried under reduced pressure at 60 °C to obtain the encapsulated powder.
[0035] (2) Preparation of hyperbranched polyimide embedding materials The embedded powder was transferred to a supercritical carbon dioxide autoclave, sealed, and then liquid carbon dioxide was introduced. The autoclave was then heated to 55°C and pressurized to 15 MPa. This supercritical state was maintained at constant temperature and pressure for 3 hours, allowing the hyperbranched polyimide to form a porous product with numerous pores.
[0036] The supercritical carbon dioxide autoclave was depressurized to atmospheric pressure at a rate of 1 MPa / min, and the resulting porous product was then transferred to a vacuum drying oven and dried at 80°C for 3 hours to obtain hyperbranched polyimide embedding material.
[0037] Example 7 A method for preparing a hyperbranched polyimide embedding material, the specific steps of which are as follows: (1) Preparation of embedded powder 0.025 g of hyperbranched polyimide (OH-HBPI) with hydroxyl end groups and 0.025 g of polyimide with anhydride end groups were dissolved in 0.6 mL of N,N-dimethylacetamide DMAc to obtain a mixed solution of hyperbranched polyimide with hydroxyl end groups and polyimide with anhydride end groups. 5 g of antioxidant 1010 was added dropwise to the mixed solution of hyperbranched polyimide with hydroxyl end groups and polyimide with anhydride end groups and stirred until homogeneous. After washing with water and filtration, the mixture was dried under reduced pressure at 60 °C to obtain the encapsulated powder.
[0038] (2) Preparation of hyperbranched polyimide embedding materials The embedded powder was transferred to a supercritical carbon dioxide autoclave, sealed, and then liquid carbon dioxide was introduced. The autoclave was then heated to 50°C and pressurized to 10 MPa. This supercritical state was maintained at constant temperature and pressure for 2 hours, allowing the hyperbranched polyimide to form a porous product with numerous pores.
[0039] The supercritical carbon dioxide autoclave was depressurized to atmospheric pressure at a rate of 1 MPa / min, and the resulting porous product was then transferred to a vacuum drying oven and dried at 80°C for 3 hours to obtain hyperbranched polyimide embedding material.
[0040] Example 8 A method for preparing a hyperbranched polyimide embedding material, the specific steps of which are as follows: (1) Preparation of embedded powder 0.025 g of hydroxyl-terminated hyperbranched polyimide (OH-HBPI) and 0.025 g of anhydride-terminated polyimide were dissolved in 0.6 mL of N,N-dimethylacetamide (DMAc) to obtain a mixed solution of hydroxyl-terminated hyperbranched polyimide and anhydride-terminated polyimide. 5 g of antioxidant 1010 was added dropwise to the mixed solution and stirred until homogeneous. After washing with water and filtration, the mixture was dried under reduced pressure at 60 °C to obtain the encapsulated powder.
[0041] (2) Preparation of hyperbranched polyimide embedding materials The embedded powder was transferred to a supercritical carbon dioxide autoclave, sealed, and then liquid carbon dioxide was introduced. The autoclave was then heated to 31°C and pressurized to 25 MPa. This supercritical state was maintained at constant temperature and pressure for 1 hour, allowing the hyperbranched polyimide to form a porous product with numerous pores.
[0042] The supercritical carbon dioxide autoclave was depressurized to atmospheric pressure at a rate of 1 MPa / min, and the resulting porous product was then transferred to a vacuum drying oven and dried at 80°C for 3 hours to obtain hyperbranched polyimide embedding material.
[0043] Example 9 The only difference between Example 9 and Example 1 is that antioxidant 1010 is replaced with antioxidant 1076.
[0044] Example 10 The only difference between Example 10 and Example 1 is that antioxidant 1010 is replaced with antioxidant 245.
[0045] Example 11 The only difference between Example 11 and Example 1 is that antioxidant 1010 is replaced by a mixture of antioxidant 1010 and antioxidant 1076 in any mass ratio.
[0046] Example 12 The only difference between Example 12 and Example 1 is that antioxidant 1010 is replaced with antioxidant 1076 and antioxidant 245, and antioxidant 1010 and antioxidant 245 are mixed in any mass ratio.
[0047] Example 13 The only difference between Example 13 and Example 2 is that n-octadecane is replaced with n-eicosane.
[0048] Example 14 The only difference between Example 14 and Example 2 is that n-octadecane is replaced with n-tetracosane.
[0049] Example 15 The only difference between Example 15 and Example 2 is that n-octadecane is replaced with n-docosahexadecane.
[0050] Example 16 The only difference between Example 16 and Example 2 is that n-octadecane is replaced with n-docosahexadecane and n-octadecane, wherein n-docosahexadecane and n-octadecane are mixed in any mass ratio.
[0051] Example 17 The only difference between Example 17 and Example 3 is that zinc oxide is replaced with iron(III) oxide.
[0052] Example 18 The only difference between Example 18 and Example 3 is that zinc oxide is replaced with vanadium pentoxide.
[0053] Example 19 The only difference between Example 19 and Example 3 is that zinc oxide is replaced with a mixture of zinc oxide and vanadium pentoxide in any mass ratio.
[0054] Example 20 The only difference between Example 20 and Example 3 is that zinc oxide is replaced with zinc oxide and iron oxide, wherein zinc oxide and iron oxide are mixed in any mass ratio.
[0055] Example 21 The only difference between Example 21 and Example 4 is that lead chromate is replaced with iron oxide.
[0056] Example 22 The only difference between Example 22 and Example 4 is that lead chromate is replaced with chromium trioxide.
[0057] Example 23 The only difference between Example 23 and Example 4 is that lead chromate is replaced with lead chromate and chromium trioxide, wherein lead chromate and chromium trioxide are mixed in any mass ratio.
[0058] Comparative Example 1 The difference between Comparative Example 1 and Example 3 is that supercritical carbon dioxide fluid treatment was not used to prepare the hyperbranched polyimide embedding material.
[0059] Hyperbranched polyimide embedding materials were successfully prepared in Examples 1 to 23 above. The hyperbranched polyimide embedding material prepared in Example 3 is now preferred for performance verification.
[0060] Experimental verification (a) Structural confirmation Infrared images before and after embedding confirm the structure.
[0061] Figure 1 The images show the infrared spectra of hyperbranched polyimide-embedded zinc oxide (SC-CO2) before and after treatment, prepared in Example 3 and Comparative Example 1 of this invention. Figure 1 As can be seen, the polyimide@ZnO powder treated with supercritical carbon dioxide underwent a change in composition at 837 cm⁻¹. -1 and 1016cm -1 ~1038cm -1 A new peak has appeared, at 837cm. -1 The appearance of the peak signifies a rearrangement of the physical structure. Supercritical CO2, as a potent physical plasticizer, penetrates into the polyimide chain segments and interfacial regions, lowering the glass transition temperature of the polymer chains and increasing chain mobility. After the pressure and temperature are removed, the molecular chains can rearrange into a more ordered and compactly packed structure, thus clearly revealing the previously masked aromatic ring characteristic peaks. (10¹⁶ cm⁻¹) -1 ~1038cm -1The emergence of the new peak indicates the occurrence of an interfacial chemical reaction, in which the chemical activity is enhanced under the high temperature and pressure of the SC-CO2 environment. It may have acted as a reaction medium and promoter, catalyzing the covalent bonding reaction between the active groups of polyimide and the hydroxyl groups on the zinc oxide surface, forming the Zn-OC interfacial layer.
[0062] 1510cm -1 The peak enhancement reflects a significant increase in the orderliness of the aromatic ring backbone arrangement. Supercritical CO2 treatment caused a highly ordered rearrangement of the aromatic ring units in the polyimide chain, enhancing π-π stacking. (1386 cm⁻¹) -1 The peak enhancement reflects the increased rigidity or regularity of the imide ring (CNC portion). The imide ring is typically linked to an aromatic ring. When the aromatic ring becomes more ordered and its planarity increases, the linked imide ring is also stretched to a more upright and flattened position, and its CN bond vibrational modes become more uniform and stronger. In summary, supercritical CO2 treatment produces a dual optimization effect on polymer composites: improved physical structural order and enhanced interfacial chemistry.
[0063] (II) Performance Verification Figure 2 The images show the BET diagrams of hyperbranched polyimide-embedded zinc oxide prepared in Example 3 and Comparative Example 1 before and after SC-CO2 treatment. Figure 2 It can be seen that the specific surface area increased significantly after supercritical treatment, from 28 m² / m³. 2 / g increased to 403m 2 / g indicates that after supercritical carbon dioxide treatment, a porous structure is formed on the coated surface, resulting in a significant increase in surface area. The increase in specific surface area increases the contact area between the modified powder and the matrix material it is composite with, leading to better compatibility and enabling the composite material to perform better.
[0064] Figure 3 The images shown are SEM images of hyperbranched polyimide-embedded zinc oxide prepared in Example 3 and Comparative Example 1 of this invention before and after SC-CO2 treatment. Figure 3 It can be seen that before coating, zinc oxide presents as rod-shaped crystals with a smooth surface. After coating, the particles become finer and have an irregular porous structure, which further proves the reason for the increase in specific surface area.
[0065] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.
Claims
1. A method for preparing a hyperbranched polyimide embedding material, characterized in that, Includes the following steps: A solution of hyperbranched polyimide with active end groups was dropped into the embedded functional material, and then filtered and dried to obtain the embedded powder. The embedded powder was placed in a supercritical carbon dioxide fluid at a temperature of 31℃~80℃ and a pressure of 8MPa~30MPa for 0.5h~6h to obtain a porous structure. The reaction pressure was then adjusted to atmospheric pressure at a depressurization rate of 0.1MPa / min~2MPa / min and dried to obtain a hyperbranched polyimide embedded material. The hyperbranched polyimide with active end groups is at least one of the following: polyimide with hydroxyl end groups, polyimide with siloxane end groups, and polyimide with anhydride end groups.
2. The method for preparing the hyperbranched polyimide embedding material according to claim 1, characterized in that, The hyperbranched polyimide solution with active end groups is prepared by dissolving hyperbranched polyimide with active end groups in an organic solvent. The mass concentration of the hyperbranched polyimide solution with active end groups is 1% to 20%, and the organic solvent is at least one of N,N-dimethylacetamide, N-methylpyrrolidone, or N,N-dimethylformamide.
3. The method for preparing the hyperbranched polyimide embedding material according to claim 1, characterized in that, The mass percentage of hyperbranched polyimide with active end groups to the embedded functional material in the solution of the hyperbranched polyimide with active end groups is 0.08% to 1.5%.
4. The method for preparing the hyperbranched polyimide embedding material according to claim 1, characterized in that, The embedded precursor is processed in supercritical carbon dioxide fluid at a temperature of 35℃~60℃, a pressure of 10MPa~25MPa, and a duration of 1h~4h.
5. The method for preparing the hyperbranched polyimide embedding material according to claim 1, characterized in that, The pressure reduction rate is 1 MPa / min, the drying temperature is 80℃~100℃, and the drying time is 2h~5h.
6. The method for preparing the hyperbranched polyimide embedding material according to claim 1, characterized in that, The encapsulating functional material is one of a dye, a phase change material, a catalyst, or an antioxidant, wherein the antioxidant is at least one of antioxidant 245, antioxidant 1010, or antioxidant 1076; the phase change material is at least one of n-octadecane, n-tetracosane, n-eicosane, or oxidized polyethylene wax; the catalyst is at least one of iron(II,III) oxide, vanadium(II,III) oxide, or zinc(II) oxide; and the dye is at least one of iron(II,III) oxide, lead(II,III) chromate, or chromium(II,III) oxide.
7. The hyperbranched polyimide embedding material is prepared by the method according to any one of claims 1 to 6.
8. The hyperbranched polyimide embedding material according to claim 7, characterized in that, The specific surface area of the hyperbranched polyimide embedding material is 10 m² / g to 500 m² / g.
9. The application of the hyperbranched polyimide embedding material according to claim 7 as a filler or active ingredient in the preparation of composite films, functional coatings, drug delivery systems or phase change energy storage products.
10. A composite material, characterized in that, Includes the hyperbranched polyimide embedding material as described in claim 7 or 8.