Self-healing 4D printing shape memory polyetherimide material as well as preparation method and application thereof

Abstract

The invention provides a self-healing 4D printing shape memory polyetherimide material and a preparation method and application thereof, and relates to the technical field of polyetherimide materials.The preparation method comprises the steps that S1, a dianhydride monomer and a diamine monomer with the molar ratio being (3-7): (7-3) are added into a polar solvent to be evenly mixed, and a reaction system is obtained; wherein the diamine monomer comprises a diamine monomer containing a disulfide bond; the dianhydride monomer and / or the diamine monomer contain ether bonds; s2, carrying out prepolymerization on the reaction system in an inert atmosphere to obtain a polyamide acid prepolymer; and S3, carrying out thermal imidization on the polyamide acid prepolymer to obtain the self-healing 4D printing shape memory polyetherimide material. The self-healing 4D printing shape memory polyetherimide material disclosed by the invention not only has a self-healing function and can realize high-temperature damage repair, but also has excellent dielectric property and processing cycle index, and can realize the forming of a high-precision complex structure in the aviation field by adopting 4D printing.

Description

Technical Field

[0001] This invention relates to the field of polyetherimide materials technology, and in particular to a self-healing 4D printed shape memory polyetherimide material, its preparation method and application. Background Technology

[0002] Polyetherimide (PEI) is a class of high molecular weight polymers with excellent mechanical properties and radiation resistance. It exhibits good chemical stability under extreme environments and has wide applications in the automotive, electrical and electronic, and aerospace fields. Furthermore, the excellent mechanical properties, stability, and ease of processing of polyetherimide have laid a solid foundation for its application in the aerospace field.

[0003] With the development of the aerospace field, the requirements for materials in terms of lightweight and safety are becoming increasingly stringent, necessitating adjustments to traditionally propelled space-deployable structures. Existing research often improves the dielectric properties of composite materials by adding inorganic fillers to polyetherimide. However, the dielectric difference between inorganic fillers and polyetherimide leads to a decrease in breakdown strength. Furthermore, the reprocessing capacity of the thermoplastic matrix relying solely on polyetherimide is extremely low, limiting its practical applications. Moreover, the molding of complex structures and high-temperature damage remain pressing issues. Therefore, there is an urgent need to provide a self-healing 4D printing shape memory polyetherimide material, its preparation method, and its applications. Summary of the Invention

[0004] This invention provides a self-healing 4D printing shape memory polyetherimide material, its preparation method, and its application. This self-healing 4D printing shape memory polyetherimide material not only has a self-healing function, enabling high-temperature damage repair, but also possesses excellent dielectric properties and processing cycle count. Furthermore, it can be used to form high-precision complex structures in the aerospace field through 4D printing.

[0005] In a first aspect, a method for preparing a self-healing 4D-printed shape memory polyetherimide material includes the following steps:

[0006] S1. Add dianhydride monomer and diamine monomer in a molar ratio of (3-7):(7-3) to a polar solvent and mix well to obtain a reaction system; wherein, the diamine monomer includes a diamine monomer containing a disulfide bond; the dianhydride monomer and / or the diamine monomer contains an ether bond;

[0007] S2. The reaction system is prepolymerized under an inert atmosphere to obtain a polyamic acid prepolymer;

[0008] S3. The polyamic acid prepolymer is thermally imidized to obtain a self-healing 4D printing shape memory polyether imide material.

[0009] Preferably, the diamine monomer is the diamine monomer containing a disulfide bond or a mixture of the diamine monomer containing a disulfide bond and a diamine monomer without a disulfide bond;

[0010] The diamine monomer containing a disulfide bond includes at least one of 4,4'-diaminodiphenyl disulfide and 2,2'-diaminodiphenyl disulfide;

[0011] The diamine monomer that does not contain disulfide bonds includes at least one of 4,4'-diaminodiphenylmethane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, and 1,3-bis(4'-aminophenoxy)benzene.

[0012] Preferably, the dianhydride monomer comprises at least one of bisphenol A type diether dianhydride, 4,4'-biphenyl ether dianhydride, 4,4'-(hexafluoroisopropene) phthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic acid dianhydride, and 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride.

[0013] Preferably, the reaction system includes a binary copolymer system, a ternary copolymer system, or a quaternary copolymer system.

[0014] More preferably, the binary copolymer system is composed of the dianhydride monomer and the diamine monomer containing disulfide bonds in a molar ratio of (3-7):(7-3).

[0015] Preferably, the ternary copolymer system comprises a first system consisting of any two of the dianhydride monomers and the diamine monomer containing disulfide bonds, a second system consisting of the dianhydride monomer and any two of the diamine monomers containing disulfide bonds, or a third system consisting of the dianhydride monomer, the diamine monomer containing disulfide bonds, and the diamine monomer without disulfide bonds in a molar ratio of the dianhydride monomer, the diamine monomer containing disulfide bonds, and the diamine monomer without disulfide bonds.

[0016] More preferably, the molar ratio of the diamine monomer containing disulfide bonds to the diamine monomer without disulfide bonds in the third system is (4-9.5):(6-0.5).

[0017] Preferably, the quaternary copolymer system is composed of four different monomers: at least one dianhydride monomer, at least one diamine monomer containing a disulfide bond, and / or a diamine monomer without a disulfide bond.

[0018] Preferably, the method further includes: stacking the polyamic acid prepolymers obtained from at least two of the reaction systems, and then performing the thermal imidization to obtain a gradient self-healing 4D printed shape memory polyetherimide material.

[0019] Preferably, in step S2, the prepolymerization temperature is 20–30°C and the time is 20–24 h.

[0020] Preferably, in step S3, the thermal imidization is carried out by a stepwise temperature increase.

[0021] Preferably, the stepped heating is performed by increasing the temperature from 25°C to 100°C at a heating rate of 0.5–1°C / min and holding it for 0.5–1 h, then increasing the temperature from 100°C to 200°C at a heating rate of 0.5–1°C / min and holding it for 1–2 h, and then increasing the temperature from 200°C to 300°C at a heating rate of 0.5–1°C / min and holding it for 1–2 h.

[0022] In a second aspect, the present invention also provides a self-healing 4D printing shape memory polyetherimide material, which is prepared by any of the preparation methods described in the first aspect above.

[0023] Thirdly, the present invention also provides an application of a self-healing 4D printing shape memory polyetherimide material for 4D printing components required in the aerospace field.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] The self-healing 4D printing shape memory polyetherimide material provided by this invention is suitable for the aerospace field. Compared with traditional propulsion devices, this material can utilize its shape memory properties for actuation, effectively reducing the weight of deployable structures. Furthermore, its self-healing function enables damage repair, improving the reliability and service life of the fabricated structures. Simultaneously, 4D printing technology allows for the rapid and precise molding of complex structures. Moreover, to address the potential damage to deployable structures caused by the complex space environment, 4D printing can be converted into on-orbit printing, enabling space station maintenance and structural construction.

[0026] In this invention, the self-healing 4D-printed shape memory polyetherimide material introduces dynamic covalent bonds, primarily achieving self-healing properties through these bonds. Furthermore, hydrogen bonds formed by the reaction of carbonyl groups and residual amino groups in the polyetherimide assist the dynamic covalent bonds, further enhancing the self-healing efficiency. Thus, when a structure prepared from this material is damaged or destroyed, crack repair can be achieved by heating, improving structural reliability and extending its safe service life.

[0027] In this invention, the imide rings, ether bonds, and dynamic disulfide bonds in the self-healing 4D-printed shape memory polyetherimide material synergistically enhance the dielectric properties. Because the material contains imide rings, and this rigid aromatic ring structure not only provides a high-energy band gap and suppresses electronic transitions, but its regularly stacked molecular chains form a dense structure that hinders carrier migration and increases the breakdown field strength. Simultaneously, the ether bonds in the material impart flexibility to the molecular chains, balancing rigidity and processability, reducing local electric field concentration, and minimizing microcracks; moreover, the dynamic disulfide bonds can repair microcracks and eliminate weak points in the breakdown process.

[0028] In this invention, the self-healing 4D printing shape memory polyetherimide material is a thermoplastic material. However, conventional polyetherimides typically exhibit a significant decline in mechanical properties after 2-3 processing cycles. But the dynamic disulfide bonds in the polyetherimide material provided by this invention can undergo reversible breakage and recombination, thus enabling it to interact with the thermoplastic matrix. Even after 4-6 processing cycles, the retention rate of mechanical properties remains >85%. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart of a method for preparing a self-healing 4D printed shape memory polyetherimide material provided by the present invention;

[0031] Figure 2 This is the DSC curve of a self-healing 4D printed shape memory polyetherimide material provided in Embodiment 1 of the present invention;

[0032] Figure 3 This is a thermogravimetric analysis curve of a self-healing 4D printed shape memory polyetherimide material provided in Embodiment 1 of the present invention;

[0033] Figure 4 This is a schematic diagram of the temporary shape of a sheet prepared by 4D printing of a self-healing 4D printed shape memory polyetherimide material according to Embodiment 1 of the present invention;

[0034] Figure 5 This is a schematic diagram of the shape memory recovery process of a sheet prepared by 4D printing of a self-healing 4D printed shape memory polyetherimide material, as provided in Embodiment 1 of the present invention.

[0035] Figure 6This is a schematic diagram of the self-healing process of a sheet prepared by 4D printing of a self-healing 4D printed shape memory polyetherimide material according to Embodiment 1 of the present invention after being damaged. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. 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.

[0037] like Figure 1 As shown, a method for preparing a self-healing 4D printed shape memory polyetherimide material includes the following steps:

[0038] S1. Add dianhydride monomer and diamine monomer in a molar ratio of (3-7):(7-3) to a polar solvent and mix well to obtain a reaction system; wherein, the diamine monomer includes diamine monomer containing disulfide bonds; the dianhydride monomer and / or diamine monomer contain ether bonds;

[0039] S2. The reaction system is prepolymerized under an inert atmosphere to obtain polyamic acid prepolymer;

[0040] S3. The polyamic acid prepolymer is thermally imidized to obtain a self-healing 4D printing shape memory polyether imide material.

[0041] In this embodiment of the invention, the self-healing 4D printing shape memory polyetherimide material is suitable for the aerospace field. Compared with traditional drive devices, this material can utilize shape memory characteristics for drive, which can effectively reduce the weight of the deployable structure. Moreover, the self-healing function can achieve damage repair, improving the reliability and service life of the prepared structure.

[0042] In this invention, the self-healing 4D-printed shape memory polyetherimide material introduces dynamic covalent bonds, primarily achieving self-healing properties through these bonds. Furthermore, hydrogen bonds formed by the reaction of carbonyl groups and residual amino groups in the polyetherimide assist the dynamic covalent bonds, further enhancing the self-healing efficiency. Thus, when a structure prepared from this material is damaged or destroyed, crack repair can be achieved by heating, improving structural reliability and extending its safe service life.

[0043] In this invention, the imide rings, ether bonds, and dynamic disulfide bonds in the self-healing 4D-printed shape memory polyetherimide material synergistically enhance the dielectric properties. Because the material contains imide rings, and this rigid aromatic ring structure not only provides a high-energy band gap and suppresses electronic transitions, but its regularly stacked molecular chains form a dense structure that hinders carrier migration and increases the breakdown field strength. Simultaneously, the ether bonds in the material impart flexibility to the molecular chains, balancing rigidity and processability, reducing local electric field concentration, and minimizing microcracks; moreover, the dynamic disulfide bonds can repair microcracks and eliminate weak points in the breakdown process.

[0044] In this invention, the self-healing 4D printing shape memory polyetherimide material is a thermoplastic material. However, conventional polyetherimides typically exhibit a significant decline in mechanical properties after 2-3 processing cycles. But the dynamic disulfide bonds in the polyetherimide material provided by this invention can undergo reversible breakage and recombination, thus enabling it to interact with the thermoplastic matrix. Even after 4-6 processing cycles, the retention rate of mechanical properties remains >85%.

[0045] It should be noted that the molar ratio of (3~7):(7~3) refers to any value of the molar ratio of dianhydride monomer to diamine monomer from 3:7 to 7:3. For example, it can be 3:7, 3.5:6.5, 4:6, 4.5:5.5, 5:5, 5.5:4.5, 6:4, 6.5:3.5 or 7:3.

[0046] According to some preferred embodiments, the diamine monomer is a diamine monomer containing a disulfide bond or a mixed monomer of a diamine monomer containing a disulfide bond and a diamine monomer without a disulfide bond;

[0047] Diamine monomers containing disulfide bonds include at least one of 4,4'-diaminodiphenyl disulfide and 2,2'-diaminodiphenyl disulfide;

[0048] Diamine monomers without disulfide bonds include at least one of 4,4'-diaminodiphenylmethane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, and 1,3-bis(4'-aminophenoxy)benzene.

[0049] According to some preferred embodiments, the dianhydride monomer includes at least one of bisphenol A type diether dianhydride, 4,4'-biphenyl ether dianhydride, 4,4'-(hexafluoroisopropene) phthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, and 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

[0050] It should be noted that "at least one" means any one or more of them mixed in any proportion.

[0051] According to some preferred embodiments, the reaction system includes a binary copolymer system, a ternary copolymer system, or a quaternary copolymer system.

[0052] According to some preferred embodiments, the binary copolymer system consists of a dianhydride monomer and a diamine monomer containing a disulfide bond in a molar ratio of (3-7):(7-3).

[0053] According to some preferred embodiments, the ternary copolymer system includes a first system composed of any two dianhydride monomers and a diamine monomer containing disulfide bonds, a second system composed of dianhydride monomers and any two diamine monomers containing disulfide bonds, or a third system composed of dianhydride monomers, diamine monomers containing disulfide bonds, and diamine monomers without disulfide bonds in a molar ratio of dianhydride monomers, diamine monomers containing disulfide bonds, and diamine monomers without disulfide bonds.

[0054] Specifically, in the first system, the molar ratio between any two dianhydride monomers is 1:9 to 9:1, and the total molar ratio of dianhydride monomers to the molar ratio of diamine monomers is 3:7 to 7:3. In the second system, the molar ratio between any two diamine monomers containing disulfide bonds is 1:9 to 9:1, and the molar ratio of dianhydride monomers to the total molar ratio of diamine monomers is 3:7 to 7:3. In the third system, the molar number of diamine monomers containing disulfide bonds is 30% to 70% of the total molar number of the entire system (e.g., 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%), the molar number of dianhydride monomers is 30% to 70% of the total molar number of the entire system (e.g., 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%), and the remainder is diamine monomers without disulfide bonds.

[0055] According to some more preferred embodiments, the molar ratio of the diamine monomer containing disulfide bonds to the diamine monomer without disulfide bonds in the third system is (4-9.5):(6-0.5) (for example, it can be 4:6, 4.5:5.5, 5:5, 5.5:4.5, 6:4, 6.5:3.5, 7:3, 7.5:2.5, 8:2, 8.5:1.5, 9:1 or 9.5:0.5).

[0056] In this embodiment of the invention, by limiting the content of diamine monomers containing disulfide bonds in the reaction system, the self-healing 4D printing shape memory polyetherimide material is further ensured to have excellent self-healing function, so as to avoid the shape memory polyetherimide material not having self-healing function when the content of diamine monomers containing disulfide bonds is too low.

[0057] According to some preferred embodiments, the quaternary copolymer system consists of four different monomers: at least one dianhydride monomer, at least one diamine monomer containing a disulfide bond, and / or a diamine monomer not containing a disulfide bond.

[0058] Specifically, the quaternary copolymer system has five possible combinations: Case 1: Composed of three different dianhydride monomers and a diamine monomer containing disulfide bonds, wherein the molar ratio of the three dianhydride monomers is 1:1:8 to 8:1:1; Case 2: Composed of two dianhydride monomers and two diamine monomers containing disulfide bonds, wherein the molar ratio of the two dianhydride monomers is 1:9 to 9:1, and the molar ratio of the two diamine monomers containing disulfide bonds is 1:9 to 9:1; Case 3: Composed of two dianhydride monomers, a diamine monomer containing disulfide bonds, and other diamine monomers without disulfide bonds, wherein the molar ratio of the two dianhydride monomers is 1:9 to 9:1, the total molar number of dianhydride monomers is 30% to 70% of the total molar number of the system, the molar number of diamine monomers containing disulfide bonds is 30% to 70% of the total molar number of the system, and the remainder is diamine monomers without disulfide bonds. Case 4: Composed of dianhydride monomers, two diamine monomers containing disulfide bonds, and other diamine monomers without disulfide bonds. The molar ratio between the two diamine monomers containing disulfide bonds is 1:9 to 9:1. The total molar number of diamine monomers containing disulfide bonds is 30 to 70% of the total molar number of the entire system, the molar number of dianhydride monomers is 30 to 70% of the total molar number of the entire system, and the remainder is diamine monomers without disulfide bonds. Case 5: Composed of dianhydride monomers, diamine monomers containing disulfide bonds, and two other diamine monomers without disulfide bonds. The molar number of diamine monomers containing disulfide bonds is 30 to 70% of the total molar number of the entire system, the molar number of dianhydride monomers is 30 to 70% of the total molar number of the entire system, and the remainder is diamine monomers without disulfide bonds. The molar ratio between the two diamine monomers without disulfide bonds is 1:9 to 9:1. In any combination, the ratio of the total moles of dianhydride monomers to the total moles of diamine monomers is 3:7 to 7:3.

[0059] According to some preferred embodiments, the method further includes: stacking polyamic acid prepolymers obtained from at least two reaction systems, and then performing thermal imidization to obtain a gradient self-healing 4D printed shape memory polyetherimide material.

[0060] Specifically, the gradient self-healing 4D printed shape memory polyetherimide material can be a stack of polyamic acid prepolymers in binary copolymer systems and ternary copolymer systems; it can be a stack of polyamic acid prepolymers in binary copolymer systems and quaternary copolymer systems; it can be a stack of polyamic acid prepolymers in ternary copolymer systems and quaternary copolymer systems; it can be a stack of polyamic acid prepolymers in binary copolymer systems, ternary copolymer systems and quaternary copolymer systems.

[0061] This invention also involves stacking polyamic acid prepolymers prepared from two or three of the above-mentioned binary copolymer systems, ternary copolymer systems, or quaternary copolymer systems to obtain a gradient material. Then, the gradient material is thermally imidized to obtain a polyetherimide gradient material (i.e., a gradient self-healing 4D printed shape memory polyetherimide material). At this time, the molecular chains of adjacent layers interpenetrate to form a network, which can further assist disulfide bonds in improving self-polymerization efficiency. At the same time, the gradient design restricts crack propagation and effectively improves the fracture toughness of the gradient material.

[0062] According to some preferred embodiments, in step S2, the prepolymerization temperature is 20-30°C (e.g., 20°C, 22°C, 25°C, 28°C or 30°C), and the time is 20-24h (e.g., 20h, 21h, 22h, 23h or 24h).

[0063] According to some preferred embodiments, in step S3, thermal imidization is performed using a stepped temperature increase.

[0064] According to some preferred embodiments, the step heating is performed by increasing the temperature from 25°C to 100°C at a heating rate of 0.5 to 1°C / min and holding it for 0.5 to 1 hour (e.g., 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, or 1 hour), then increasing the temperature from 100°C to 200°C at a heating rate of 0.5 to 1°C / min and holding it for 1 to 2 hours (e.g., 1 hour, 1.2 hours, 1.5 hours, 1.8 hours, or 2 hours), then increasing the temperature from 200°C to 300°C at a heating rate of 0.5 to 1°C / min and holding it for 1 to 2 hours (e.g., 1 hour, 1.2 hours, 1.5 hours, 1.8 hours, or 2 hours).

[0065] It should be noted that the heating rate of 0.5 to 1℃ / min means that it can be any value from 0.5℃ / min to 1℃ / min, such as 0.5℃ / min, 0.55℃ / min, 0.6℃ / min, 0.65℃ / min, 0.7℃ / min, 0.75℃ / min, 0.8℃ / min, 0.85℃ / min, 0.9℃ / min, 0.95℃ / min or 1℃ / min.

[0066] This invention also provides a self-healing 4D-printable shape memory polyetherimide material having repeating units of the molecular structure shown below:

[0067]

[0068] Both the Ar1 and Ar2 groups contain benzene rings; at least one repeating unit of the Ar1 group and / or Ar2 group contains a disulfide bond, and the Ar1 group and / or Ar2 group contains an ether bond.

[0069] According to some preferred embodiments, each repeating unit contains a disulfide bond in the Ar1 group and / or Ar2 group, and an ether bond in the Ar1 group and / or Ar2 group.

[0070] According to some preferred embodiments

[0071]

[0072] This invention also provides an application of a self-healing 4D printing shape memory polyetherimide material for 4D printing components required in the aerospace field.

[0073] In this invention, 4D printing technology enables the rapid and precise molding of complex structures. Furthermore, to address the potential damage to deployable structures caused by the complex space environment, 4D printing can be converted into on-orbit printing, which can facilitate the maintenance and construction of space stations. Moreover, 4D printing technology is more environmentally friendly than traditional manufacturing methods, reducing raw material waste and waste generation, thus contributing to environmental pollution control.

[0074] According to some preferred embodiments, self-healing 4D printed shape memory polyetherimide materials are used to prepare space deployable components.

[0075] To more clearly illustrate the technical solution and advantages of the present invention, the following embodiments provide a detailed description of a self-healing 4D printing shape memory polyetherimide material, its preparation method, and its application.

[0076] Example 1

[0077] S1. Dry all equipment and materials at high temperature to remove moisture, ensuring strict dehydration. Add 4,4'-diaminodiphenyl disulfide and bisphenol A type diether dianhydride in a molar ratio of 1:1 to three-necked flasks, add excess N,N-dimethylacetamide, and stir until homogeneous to obtain the reaction system;

[0078] S2. Nitrogen gas is introduced into the reaction system and stirred continuously. The reaction is carried out at 25°C for 20 hours to obtain polyamic acid prepolymer.

[0079] S3. Pour the obtained polyamic acid prepolymer into a flat container and gradually increase the temperature to 300℃ for thermal imidization to obtain a self-healing 4D printing shape memory polyether imide material. The specific steps of the gradual heating are as follows: increase the temperature from 25℃ to 100℃ at a heating rate of 0.5℃ / min and hold for 0.5h; continue to increase the temperature from 100℃ to 200℃ at a heating rate of 0.5℃ / min and hold for 1h; continue to increase the temperature from 200℃ to 300℃ at a heating rate of 0.5℃ / min and hold for 1h.

[0080] Example 2

[0081] S1. Dry all utensils and materials at high temperature to remove moisture, ensuring thorough dehydration. Add 4,4'-diaminodiphenyl disulfide, 4,4'-diaminodiphenyl ether and 4,4'-(hexafluoroisopropene) phthalic anhydride in a molar ratio of 2:1:3 to three-necked flasks, add excess N,N-dimethylacetamide, and stir until homogeneous to obtain the reaction system;

[0082] S2. Nitrogen gas is introduced into the reaction system and stirred continuously. The reaction is carried out at 25°C for 20 hours to obtain polyamic acid prepolymer.

[0083] S3. Pour the obtained polyamic acid prepolymer into a flat container and gradually increase the temperature to 300℃ for thermal imidization to obtain a self-healing 4D printing shape memory polyether imide material. The specific steps of the gradual heating are as follows: increase the temperature from 25℃ to 100℃ at a heating rate of 0.5℃ / min and hold for 0.5h; continue to increase the temperature from 100℃ to 200℃ at a heating rate of 0.5℃ / min and hold for 1h; continue to increase the temperature from 200℃ to 300℃ at a heating rate of 0.5℃ / min and hold for 1h.

[0084] Example 3

[0085] S1. Dry all equipment and materials at high temperature to remove moisture, ensuring thorough dehydration. Add 4,4'-diaminodiphenyl disulfide, 4,4'-diaminodiphenylmethane, 4,4'-biphenyl ether dianhydride and bisphenol A type diether dianhydride in a molar ratio of 1:1:1:1 to three-necked flasks, add excess N,N-dimethylacetamide, and stir until homogeneous to obtain the reaction system;

[0086] S2. Nitrogen gas is introduced into the reaction system and stirred continuously. The reaction is carried out at 25°C for 20 hours to obtain polyamic acid prepolymer.

[0087] S3. Pour the obtained polyamic acid prepolymer into a flat container and gradually increase the temperature to 300℃ for thermal imidization to obtain a self-healing 4D printing shape memory polyether imide material. The specific steps of the gradual heating are as follows: increase the temperature from 25℃ to 100℃ at a heating rate of 0.5℃ / min and hold for 0.5h; continue to increase the temperature from 100℃ to 200℃ at a heating rate of 0.5℃ / min and hold for 1h; continue to increase the temperature from 200℃ to 300℃ at a heating rate of 0.5℃ / min and hold for 1h.

[0088] Example 4

[0089] S1. Dry all utensils and materials at high temperature to remove moisture, ensuring thorough dehydration. Add 4,4'-diaminodiphenyl disulfide and bisphenol A type diether dianhydride in a molar ratio of 1:1 to a three-necked flask, add excess N,N-dimethylacetamide, and stir until homogeneous to obtain a binary copolymer system; add 4,4'-diaminodiphenyl disulfide, 4,4'-diaminodiphenyl ether, and 4,4'-(hexafluoroisopropene) diaphthalic anhydride in a molar ratio of 2:1:3 to a three-necked flask, add excess N,N-dimethylacetamide, and stir until homogeneous to obtain a ternary copolymer system;

[0090] S2. Nitrogen gas is continuously introduced into the binary copolymer system and stirred, and the reaction is carried out at 25°C for 20 hours to obtain the binary polyamic acid prepolymer; nitrogen gas is continuously introduced into the ternary copolymer system and stirred, and the reaction is carried out at 25°C for 20 hours to obtain the ternary polyamic acid prepolymer.

[0091] S3. Pour the binary polyamic acid prepolymer into a flat container. While it is still wet, quickly pour in the ternary polyamic acid prepolymer to obtain a gradient prepolymer. Then, gradually increase the temperature to 300℃ for thermal imidization to obtain a gradient self-healing 4D printing shape memory polyether imide material. The specific steps of the gradual heating are as follows: increase the temperature from 25℃ to 100℃ at a heating rate of 0.5℃ / min and hold for 0.5h; continue to increase the temperature from 100℃ to 200℃ at a heating rate of 0.5℃ / min and hold for 1h; continue to increase the temperature from 200℃ to 300℃ at a heating rate of 0.5℃ / min and hold for 1h.

[0092] Example 5

[0093] Example 5 is basically the same as Example 1, except that the specific steps of the step heating are as follows: the temperature is increased from 25°C to 100°C at a heating rate of 1°C / min and held for 1 hour; the temperature is then increased from 100°C to 200°C at a heating rate of 1°C / min and held for 2 hours; and the temperature is then increased from 200°C to 300°C at a heating rate of 1°C / min and held for 2 hours.

[0094] Comparative Example 1

[0095] Comparative Example 1 is basically the same as Example 1, except that in step S1, 4,4'-diaminodiphenyl disulfide is replaced with 4,4'-diaminodiphenylmethane.

[0096] Comparative Example 2

[0097] Comparative Example 2 is basically the same as Example 1, except that in step S1, 4,4'-diaminodiphenylmethane and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride are used in a molar ratio of 1:1.

[0098] Comparative Example 3

[0099] Comparative Example 3 is basically the same as Example 2, except that in step S1, 4,4'-diaminodiphenylmethane and 4,4'-(hexafluoroisopropene) phthalic anhydride are used in a molar ratio of 3:3.

[0100] The self-healing 4D-printable shape memory polyetherimide materials prepared in Examples 1 to 5 of this invention all possess shape memory and high-temperature self-healing functions, and exhibit excellent dielectric properties. The self-healing 4D-printable shape memory polyetherimide material prepared in Example 1 was fabricated into a sheet 20 mm long and 1 mm thick using a 4D printing method. Figure 2 The DSC curve of the sheet is shown; Figure 3 The thermogravimetric analysis curve of the sheet is shown; Figure 4 The temporary shape obtained by bending the sheet at 250°C and then fixing it at room temperature is shown. Figure 5 The process of the sheet recovering after heating at 250°C is shown. Figure 6 The self-healing effect of the sheet at 250°C after it breaks in the middle is shown.

[0101] Tests on the above-mentioned self-healing 4D-printed shape memory polyetherimide materials showed that, under a test frequency of 1MHz, the dielectric constant of the self-healing 4D-printed shape memory polyetherimide materials in Examples 1 and 5 was approximately 2.6–3.2, and the dielectric loss was approximately 0.004–0.006. The dielectric constant of the self-healing 4D-printed shape memory polyetherimide material in Example 2 was approximately 2.3–2.5, and the dielectric loss was approximately 0.003–0.005. The dielectric constant of the self-healing 4D-printed shape memory polyetherimide material in Example 3 was approximately 2.7–3.0, and the dielectric loss was approximately 0.004–0.007. The dielectric constant of the self-healing 4D-printed shape memory polyetherimide material in Example 4 was approximately 2.4–2.8, and the dielectric loss was approximately 0.003–0.005.

[0102] The shape memory polyetherimide material of Comparative Example 1 exhibits a dielectric constant of approximately 3.0–3.5 and a dielectric loss of approximately 0.006–0.008 at a test frequency of 1 MHz. The shape memory polyimide material of Comparative Example 2 exhibits a dielectric constant of approximately 2.8–3.3 and a dielectric loss of approximately 0.006–0.008 at a test frequency of 1 MHz. The shape memory polyimide material of Comparative Example 3 exhibits a dielectric constant of approximately 2.6–3.0 and a dielectric loss of approximately 0.004–0.006 at a test frequency of 1 MHz. Compared to Example 1, Comparative Example 1 did not introduce disulfide bonds, and Comparative Example 2 did not introduce ether bonds or disulfide bonds; compared to Example 2, Comparative Example 3 did not introduce ether bonds or disulfide bonds. The materials prepared in this way not only lack self-healing functionality, but also have dielectric constants higher than those of the aforementioned examples. Therefore, this further confirms the synergistic effect of the three groups—imide ring, ether bond, and disulfide bond—which effectively improves dielectric properties. By cyclically processing the materials prepared in Example 1 and Comparative Example 1, it was found that the conventional polyetherimide in Comparative Example 1 showed a significant decrease in mechanical properties after 2-3 cycles (the retention rate of mechanical properties was 60-80%), but the polyetherimide material provided in Example 1 still had a mechanical property retention rate of >85% after 4-6 cycles.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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; and these 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 the present invention.

Claims

1. A method for preparing a self-healing 4D printed shape memory polyetherimide material, characterized in that, The preparation method includes the following steps: S1. Add dianhydride monomer and diamine monomer in a molar ratio of (3-7):(7-3) to a polar solvent and mix well to obtain a reaction system; wherein, the diamine monomer includes a diamine monomer containing a disulfide bond; the dianhydride monomer and / or the diamine monomer contains an ether bond; S2. The reaction system is prepolymerized under an inert atmosphere to obtain a polyamic acid prepolymer; S3. The polyamic acid prepolymer is thermally imidized to obtain a self-healing 4D printing shape memory polyether imide material.

2. The preparation method according to claim 1, characterized in that, The diamine monomer is either the diamine monomer containing a disulfide bond or a mixture of the diamine monomer containing a disulfide bond and a diamine monomer without a disulfide bond; The diamine monomer containing a disulfide bond includes at least one of 4,4'-diaminodiphenyl disulfide and 2,2'-diaminodiphenyl disulfide; The diamine monomer that does not contain disulfide bonds includes at least one of 4,4'-diaminodiphenylmethane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, and 1,3-bis(4'-aminophenoxy)benzene.

3. The preparation method according to claim 1, characterized in that, The dianhydride monomer includes at least one of bisphenol A type diether dianhydride, 4,4'-biphenyl ether dianhydride, 4,4'-(hexafluoroisopropene) phthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, and 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

4. The preparation method according to claim 1, characterized in that, The reaction system includes a binary copolymer system, a ternary copolymer system, or a quaternary copolymer system; Preferably, the binary copolymer system is composed of the dianhydride monomer and the diamine monomer containing disulfide bonds in a molar ratio of (3-7):(7-3).

5. The preparation method according to claim 4, characterized in that, The ternary copolymer system includes a first system composed of any two of the dianhydride monomers and the diamine monomer containing disulfide bonds, a second system composed of the dianhydride monomer and any two of the diamine monomers containing disulfide bonds, or a third system composed of the dianhydride monomer, the diamine monomer containing disulfide bonds, and the diamine monomer without disulfide bonds in a molar ratio of the dianhydride monomer, the diamine monomer containing disulfide bonds, and the diamine monomer without disulfide bonds. Preferably, the molar ratio of the diamine monomer containing disulfide bonds to the diamine monomer without disulfide bonds in the third system is (4-9.5):(6-0.5).

6. The preparation method according to claim 4, characterized in that, The quaternary copolymer system is composed of four different monomers: at least one of the dianhydride monomers, at least one of the diamine monomers containing disulfide bonds, and / or a diamine monomer without disulfide bonds.

7. The preparation method according to claim 4, characterized in that, Also includes: The polyamic acid prepolymers obtained from at least two of the aforementioned reaction systems are stacked and then subjected to thermal imidization to obtain a gradient self-healing 4D printed shape memory polyetherimide material.

8. The preparation method according to any one of claims 1 to 7, wherein in step S2, the prepolymerization temperature is 20–30°C and the time is 20–24 h; and / or, In step S3, the thermal imidization is carried out by a stepwise temperature increase; preferably, the stepwise temperature increase is to increase the temperature from 25°C to 100°C at a heating rate of 0.5 to 1°C / min and hold it for 0.5 to 1 hour, then continue to increase the temperature from 100°C to 200°C at a heating rate of 0.5 to 1°C / min and hold it for 1 to 2 hours, then continue to increase the temperature from 200°C to 300°C at a heating rate of 0.5 to 1°C / min and hold it for 1 to 2 hours.

9. A self-healing 4D-printed shape memory polyetherimide material, characterized in that, It is prepared by any one of the preparation methods according to claims 1 to 8.

10. The application of a self-healing 4D printing shape memory polyetherimide material prepared by the preparation method according to any one of claims 1 to 8, characterized in that, Used for 4D printing to manufacture components required in the aerospace field, preferably for manufacturing space deployable components.

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