ZIF-8 / PEN composite honeycomb hole film as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of thin film materials, and relates to a ZIF-8 / PEN composite honeycomb hole thin film and a preparation method and application thereof, and the preparation method comprises the following steps: S1, preparing PVP K30 / ZIF-8; s2, dispersing PVP K30 / ZIF-8 into N-methyl pyrrolidone, performing ultrasonic treatment, then sequentially adding polyarylene ether nitrile and a triblock copolymer nonionic surfactant, and performing heating stirring and normal-temperature stirring to obtain a mixed solution; and S3, performing membrane scraping on the mixed solution, and then forming a membrane in a coagulating bath to obtain the ZIF-8 / PEN composite honeycomb pore membrane. According to the invention, the ZIF-8 / PEN composite honeycomb pore film is prepared by a phase inversion technology, has low dielectric constant, excellent mechanical strength and durability and low cost, and can be used in high-frequency electronic equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of film materials and relates to a ZIF-8 / PEN composite honeycomb film and a preparation method and application thereof. Background Art

[0002] Dielectric materials are key components in electronic devices, and the performance of dielectric materials plays a decisive role in the efficiency and stability of signal transmission; especially in high-frequency signal transmission applications, the dielectric constant (k value) of the material has become a crucial performance parameter.

[0003] At present, polymer dielectric materials are widely used due to their good processing properties and mechanical flexibility. Polyarylethernitrile (PEN), as a high-performance polymer, occupies a place in electronic insulating materials due to its excellent thermal stability and mechanical strength. However, the dielectric constant of PEN is relatively high, which limits the signal transmission speed, resulting in increased energy loss and cannot meet the needs of high-frequency electronic applications. Therefore, in order to reduce the dielectric constant of PEN, researchers have carried out deep processing on PEN, usually using chemical modification and physical filling. For chemical modification: the dielectric constant of PEN is reduced by changing the structure of the molecular chain, but this method may increase the preparation cost of the material and bring complexity to the processing process. For physical filling: fillers with low dielectric constants are dispersed in the PEN matrix to form a composite material, in the hope of improving the dielectric properties of the material through the characteristics of the filler. For example, metal organic frameworks (MOFs) materials are used as fillers, especially zeolite imidazole framework-8 (ZIF-8) is dispersed in the PEN matrix. Since ZIF-8 has a low dielectric constant and a high specific surface area, however, when ZIF-8 is directly doped into the polymer matrix as a filler, there will be technical difficulties such as insufficient dispersion uniformity and poor interface compatibility. Poor dispersion will cause the filler to aggregate in the matrix, and poor interface compatibility may lead to a weakened bond between the filler and the polymer matrix, ultimately affecting the mechanical strength and durability of the material; ultimately resulting in reduced overall mechanical properties of the composite material and poor flexibility, especially in application environments that need to withstand mechanical stress, such as flexible electronics and wearable devices.

[0004] It can be seen from the above disclosed contents that the methods of reducing the dielectric constant of PEN in the prior art still have the problems of poor mechanical properties and flexibility of the composite material and high cost. Summary of the invention

[0005] Aiming at the technical problems that the existing method for reducing the dielectric constant of PEN has poor mechanical properties, poor flexibility and high cost of the composite material, the present invention provides a ZIF-8 / PEN composite honeycomb porous film and a preparation method and application thereof.

[0006] The present invention uses polyvinyl pyrrolidone to modify ZIF-8, and then mixes it with polyarylethernitrile and triblock copolymer, and then prepares ZIF-8 / PEN composite honeycomb porous film through phase inversion technology. The film has low dielectric constant, excellent mechanical strength and durability, low cost, and can be used in high-frequency electronic equipment.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing a ZIF-8 / PEN composite honeycomb porous film comprises the following steps:

[0009] S1. Preparation of PVP K30 / ZIF-8

[0010] Take Zn(NO3)2·6H2O, polyvinyl pyrrolidone, 2-methylimidazole and a polar solvent, and obtain powdered PVP K30 / ZIF-8 by a step-by-step mixing method; the mass volume ratio of the Zn(NO3)2·6H2O, polyvinyl pyrrolidone, 2-methylimidazole and the polar solvent is (2-3) g: 1 g: (3-6) g: 200 ml;

[0011] S2. Preparation of mixed solution

[0012] The PVP K30 / ZIF-8 prepared in step S1 is dispersed in N-methylpyrrolidone, and after ultrasonic treatment, poly(arylene ether nitrile) and triblock copolymer nonionic surfactant are added in sequence, and heated and stirred at room temperature to obtain a mixed solution; the mass ratio of the PVP K30 / ZIF-8, PEN and triblock copolymer nonionic surfactant is (10-20):100:10;

[0013] Preparation of S3, ZIF-8 / PEN composite honeycomb film

[0014] The mixed solution obtained in step S2 is poured onto a glass plate, and a uniform liquid film with a thickness of 250 μm is scraped out, which is placed in a coagulation bath to form a solid film, and then allowed to stand and dry to obtain a ZIF-8 / PEN composite honeycomb porous film.

[0015] It is further defined that in step S1, the step-by-step mixing method is specifically:

[0016] S1.1, dissolving Zn(NO3)2·6H2O and polyvinyl pyrrolidone in a polar solvent to obtain solution A; in solution A, the mass ratio of Zn(NO3)2·6H2O to polyvinyl pyrrolidone is (4-6):1;

[0017] S1.2, dissolving 2-methylimidazole and polyvinyl pyrrolidone in a polar solvent to obtain a solution B; in the solution B, the mass ratio of 2-methylimidazole to polyvinyl pyrrolidone is (6-12):1;

[0018] S1.3, after mixing solution A and solution B, stirring and standing to obtain ZIF-8 crystals; and then washing and drying to obtain powdered PVP K30 / ZIF-8;

[0019] It is further defined that in step S1.3, the stirring time is 1 h to 2 h, the standing time is 12 h to 36 h, the washing is 3 to 5 times, the drying temperature is 20° C. to 40° C., and the drying time is 4 h to 8 h.

[0020] It is further defined that the polar solvent is any one of methanol, water and N,N-dimethylformamide; the triblock copolymer nonionic surfactant is any one of triblock copolymer Pluronic F-98, triblock copolymer Pluronic F-108 and triblock copolymer Pluronic F-127; the coagulation bath is an ethanol solution, and the volume fraction of ethanol in the ethanol solution is 20% to 100%.

[0021] It is further defined that in step S2, the ultrasonic time is 1h to 2h, the heating stirring speed and the room temperature stirring speed are both 100r / min to 300r / min, the stirring temperature is 30 to 80°C, the heating stirring time is 1h to 2h, and the room temperature stirring time is 30min to 60min.

[0022] It is further defined that in step S3, the standing time is 12 hours to 36 hours, the drying temperature is 20° C. to 40° C., and the drying time is 6 hours to 8 hours.

[0023] The ZIF-8 / PEN composite honeycomb porous film is prepared by utilizing the preparation method of the ZIF-8 / PEN composite honeycomb porous film.

[0024] It is further defined that the ZIF-8 / PEN composite honeycomb film is a honeycomb structure or a finger-like pore structure, with a pore size of 4.9 μm to 6.2 μm and a thickness of 0.25±0.05 mm.

[0025] It is further defined that the ZIF-8 / PEN composite honeycomb film has a minimum dielectric constant of 1.39, a maximum tensile strength of 10 MPa, and a maximum elongation at break of 108.3%.

[0026] As described above, the ZIF-8 / PEN composite honeycomb film is used in flexible ultra-low dielectric materials.

[0027] The beneficial effects of the present invention are:

[0028] 1. The present invention uses phase inversion technology to modify ZIF-8 with polyvinyl pyrrolidone (PVP K30), and then mixes it with poly(arylether nitrile) (PEN) and a triblock copolymer to prepare a ZIF-8 / PEN composite honeycomb porous film with a rich microporous structure. The film is easy to operate and has low cost. It has a low dielectric constant and meets the application requirements of high-frequency electronic equipment. It also has excellent mechanical strength and durability, and shows great application potential in the field of high-performance electronic insulating materials.

[0029] 2. The ZIF-8 / PEN composite honeycomb porous film prepared by the present invention has a honeycomb structure, which not only effectively reduces the overall density of the material, but also promotes the uniform dispersion of ZIF-8 in the polyarylethernitrile skeleton, so that the dielectric constant (k value) of the composite film is significantly reduced while maintaining excellent mechanical properties.

[0030] 3. The ZIF-8 / PEN composite film of the present invention has a microporous structure with adjustable morphology, and its pore characteristics change significantly with the increase of the proportion of ethanol in the coagulation bath. The microporous morphology evolves from honeycomb pores to vertical finger-like pore structures, and the size increases from 1.6 μm to 5.8 μm.

[0031] 4. The present invention significantly reduces the dielectric constant of the ZIF-8 / PEN composite film from 1.69 to 1.39 by adjusting the amount of ZIF-8, while maintaining an elongation at break of more than 108% and excellent flexibility, allowing the material to be folded repeatedly without breaking. These properties meet the strict requirements of low dielectric constant materials and provide significant advantages for the development of next-generation flexible poly(arylene ether nitrile) materials.

[0032] 5. The preparation method of the present invention is simple and easy to operate, and has wide applicability. It is suitable for mixing different polymer matrices and fillers, and shows good industrial production potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic cross-sectional view of a ZIF-8 / PEN composite honeycomb porous film;

[0034] Figure 2 1 is a dielectric constant diagram of ZIF-8 / PEN composite honeycomb porous film; wherein: in implementation examples 1 to 3, the ZIF-8 content gradually increases from 10% to 20%, and all are in a 30% ethanol bath, expressed as Fe-p;

[0035] Figure 3 This is a plan view of the ZIF-8 / PEN composite honeycomb film after repeated folding. DETAILED DESCRIPTION

[0036] The following are examples of the preparation method of the present invention. However, the following examples are only used to illustrate the present invention and do not constitute any limitation to the claims of the present invention.

[0037] The present invention provides a method for preparing a ZIF-8 / PEN composite honeycomb porous film, comprising the following steps:

[0038] S1. Preparation of PVP K30 / ZIF-8

[0039] Zn(NO3)2·6H2O, polyvinylpyrrolidone PVP K30, 2-methylimidazole and a polar solvent were taken and powdered PVP K30 / ZIF-8 was obtained by a step-by-step mixing method.

[0040] Preferably, the mass volume ratio of Zn(NO3)2·6H2O, polyvinylpyrrolidone PVP K30, 2-methylimidazole and polar solvent is (2-3) g: 1 g: (3-6) g: 200 ml.

[0041] In step S1 of the present invention, the step-by-step mixing method is specifically:

[0042] S1.1. Dissolve Zn(NO3)2·6H2O and polyvinylpyrrolidone PVP K30 in a polar solvent to obtain solution A; in solution A, the mass ratio of Zn(NO3)2·6H2O and polyvinylpyrrolidone PVP K30 is (4-6):1.

[0043] S1.2, dissolving 2-methylimidazole and polyvinylpyrrolidone PVP K30 in a polar solvent to obtain solution B; in solution B, the mass ratio of 2-methylimidazole to polyvinylpyrrolidone PVP K30 is (6-12):1.

[0044] S1.3, after mixing solution A and solution B, stirring and standing to obtain ZIF-8 crystals; and then washing and drying to obtain powdered PVP K30 / ZIF-8.

[0045] Preferably, in step S1.3, the stirring time is 1 h to 2 h, the standing time is 12 h to 36 h, the washing is 3 to 5 times, the drying temperature is 20° C. to 40° C., and the drying time is 4 h to 8 h.

[0046] Preferably, the polar solvent is any one of methanol, water and N,N-dimethylformamide.

[0047] S2. Preparation of mixed solution

[0048] The PVP K30 / ZIF-8 prepared in step S1 is dispersed in N-methylpyrrolidone, and after ultrasonic treatment, poly(arylene ether nitrile) PEN and triblock copolymer nonionic surfactant are added in sequence, and heated and stirred at room temperature to obtain a mixed solution.

[0049] Preferably, the mass ratio of PVP K30 / ZIF-8, PEN and triblock copolymer nonionic surfactant is (10-20):100:10.

[0050] Preferably, the triblock copolymer nonionic surfactant is any one of the triblock copolymer Pluronic F-98, the triblock copolymer Pluronic F-108 and the triblock copolymer Pluronic F-127.

[0051] In step S2 of the present invention, the ultrasonic time is 1h to 2h, the heating stirring speed and the room temperature stirring speed are both 100r / min to 300r / min, the stirring temperature is 30 to 80°C, the heating stirring time is 1h to 2h, and the room temperature stirring time is 30min to 60min.

[0052] Preparation of S3, ZIF-8 / PEN composite honeycomb film

[0053] The mixed solution obtained in step S2 is poured onto a glass plate, and a uniform liquid film with a thickness of 250 μm is scraped out, which is placed in a coagulation bath to form a solid film, and then allowed to stand and dry to obtain a ZIF-8 / PEN composite honeycomb porous film.

[0054] Preferably, the coagulation bath is an ethanol solution, and the volume fraction of ethanol in the ethanol solution is 20% to 100%.

[0055] Preferably, in step S3, the standing time is 12 h to 36 h, the drying temperature is 20° C. to 40° C., and the drying time is 6 h to 8 h.

[0056] The ZIF-8 / PEN composite honeycomb porous film prepared by the above method in the present invention has a honeycomb structure or a finger-like pore structure, a pore size of 4.9μm to 6.2μm, and a thickness of 0.25±0.05mm; the lowest dielectric constant is 1.39, the highest tensile strength is 10MPa, the highest elongation at break is 108.3%, and it can be folded repeatedly for many times without breaking, and can be used as a flexible ultra-low dielectric material in electronic devices.

[0057] The above technical solution of the present invention is described in detail with several groups of specific embodiments below.

[0058] It should be noted that, unless otherwise specified, the drugs, reagents, etc. used in the following examples are all conventional commercially available products in the art.

[0059] It should be noted that, unless otherwise specified, the operating processes used in the following embodiments, such as stirring, drying, mixing, etc., are all conventional operations in the art.

[0060] Example 1

[0061] The method for preparing the ZIF-8 / PEN composite honeycomb porous film provided in this embodiment comprises the following steps:

[0062] S1. Preparation of PVP K30 / ZIF-8

[0063] 0.3g Zn(NO3)2·6H2O and 0.05g PVP K30 were added to 10ml methanol, and 0.66g 2-methylimidazole and 0.05g PVP K30 were added to 10ml methanol respectively. They were stirred for 1h and allowed to stand for 1min. Then, the 2-methylimidazole solution was added to the Zn(NO3)2·6H2O solution. The combined solution was stirred for 1min and then allowed to react for 24h. The white powder was washed three times with methanol. The powder obtained by filtering the mixed solution was placed in an oven at 30°C and dried for 6h to obtain ZIF-8 powder with surface modified with PVP K30.

[0064] S2. Preparation of mixed solution

[0065] Weigh 0.1 g of PVP K30 / ZIF-8 into a 20 ml glass bottle, add 10 ml of N-methylpyrrolidone, and disperse ultrasonically for 2 h. Then, add 0.9 g of PEN and 0.1 g of triblock copolymer F-127 (Pluronic F-127) to the ZIF-8 mixed solution. Place the glass bottle containing the mixed solution on a magnetic heating stirrer, heat and stir at 60 ° C for 1 h, turn off the heating, and stir at room temperature for 30 min to obtain a PVP K30 / ZIF-8 / PEN / Pluronic F-127 mixed solution.

[0066] Preparation of S3, ZIF-8 / PEN composite honeycomb membrane

[0067] The PVP K30 / ZIF-8 / PEN / Pluronic F-127 mixed solution obtained in step S2 is poured onto a glass plate, and a 250 μm uniform liquid film is scraped using a wet film preparation device, and then the glass plate and the liquid film on its surface are immersed in a coagulation bath, wherein the coagulation bath is 2000 ml of pure ethanol, that is, the volume proportion of ethanol is 100%; after the liquid film is converted into a solid film, it is peeled off from the glass plate, and it continues to be immersed in the coagulation bath for 36 hours, and then it is placed in a vacuum oven at 50° C. to dry for 8 hours, and naturally cooled to room temperature to obtain a ZIF-8 / PEN composite honeycomb porous film.

[0068] Example 2

[0069] The method for preparing the ZIF-8 / PEN composite honeycomb porous film provided in this embodiment comprises the following steps:

[0070] S1. The preparation of PVP K30 / ZIF-8 is consistent with the process in Example 1.

[0071] S2. Preparation of mixed solution

[0072] Weigh 0.15g PVP K30 / ZIF-8 into a 20ml glass bottle, add 10ml N-methylpyrrolidone (NMP), and disperse by ultrasonic for 2h. Then add 0.85g PEN and 0.1g Pluronic F-127 to the ZIF-8 mixed solution, place the glass bottle containing the mixed solution on a magnetic heating stirrer, heat and stir at 60℃ for 1h, turn off the heating and stir at room temperature for 30min to obtain a PVP K30 / ZIF-8 / PEN / Pluronic F-127 mixed solution.

[0073] S3. The preparation of ZIF-8 / PEN composite honeycomb membrane is consistent with the process in Example 1.

[0074] Example 3

[0075] The method for preparing the ZIF-8 / PEN composite honeycomb porous film provided in this embodiment comprises the following steps:

[0076] S1. The preparation of PVP K30 / ZIF-8 is consistent with the process in Example 1.

[0077] S2. Preparation of mixed solution

[0078] Weigh 0.2g PVP K30 / ZIF-8 into a 20ml glass bottle, add 10ml N-methylpyrrolidone, and disperse by ultrasonic for 2h. Then add 0.8g PEN and 0.1g Pluronic F-127 to the ZIF-8 mixed solution, place the glass bottle containing the mixed solution on a magnetic heating stirrer, heat and stir at 60℃ for 1h, turn off the heating and stir at room temperature for 30min to obtain a PVP K30 / ZIF-8 / PEN / Pluronic F-127 mixed solution.

[0079] S3. The preparation of ZIF-8 / PEN composite honeycomb membrane is consistent with the process in Example 1.

[0080] Example 4

[0081] Compared with Example 1, the method for preparing the ZIF-8 / PEN composite honeycomb porous film provided in this embodiment only changes the ratio of the coagulation bath.

[0082] In this embodiment, the ratio of the coagulation bath is 1600 ml of deionized water and 400 ml of pure ethanol; that is, the volume proportion of ethanol is 20%.

[0083] Example 5

[0084] Compared with Example 2, the method for preparing the ZIF-8 / PEN composite honeycomb porous film provided in this embodiment only changes the ratio of the coagulation bath.

[0085] In this embodiment, the ratio of the coagulation bath is 1600 ml of deionized water and 400 ml of pure ethanol, that is, the volume proportion of ethanol is 20%.

[0086] Example 6

[0087] Compared with Example 3, the method for preparing the ZIF-8 / PEN composite honeycomb porous film provided in this embodiment only changes the ratio of the coagulation bath.

[0088] In this embodiment, the ratio of the coagulation bath is 1600 ml of deionized water and 400 ml of pure ethanol, that is, the volume proportion of ethanol is 20%.

[0089] Example 7

[0090] Compared with Example 1, the method for preparing the ZIF-8 / PEN composite honeycomb porous film provided in this embodiment only changes the ratio of the coagulation bath.

[0091] In this embodiment, the ratio of the coagulation bath is 1400 ml of deionized water and 600 ml of pure ethanol, that is, the volume proportion of ethanol is 30%.

[0092] Example 8

[0093] Compared with Example 2, the method for preparing the ZIF-8 / PEN composite honeycomb porous film provided in this embodiment only changes the ratio of the coagulation bath.

[0094] In this embodiment, the ratio of the coagulation bath is 1400 ml of deionized water and 600 ml of pure ethanol, that is, the volume proportion of ethanol is 30%.

[0095] Example 9

[0096] Compared with Example 3, the method for preparing the ZIF-8 / PEN composite honeycomb porous film provided in this embodiment only changes the ratio of the coagulation bath.

[0097] In this embodiment, the ratio of the coagulation bath is 1400 ml of deionized water and 600 ml of pure ethanol, that is, the volume proportion of ethanol is 30%.

[0098] Further, Examples 1 to 9 are ZIF-8 / PEN composite honeycomb porous films prepared under different coagulation baths with different ZIF-8 contents. In order to prove the performance of the ZIF-8 / PEN composite honeycomb porous film prepared by the present invention, the following test verification is performed. In the test verification, the following comparative example is also set to compare with the ZIF-8 / PEN composite honeycomb porous film of the present invention.

[0099] Comparative Example 1

[0100] The preparation method of the ZIF-8 / PEN composite honeycomb porous film provided in this comparative example comprises the following steps:

[0101] S1. Preparation of PVP K30 / ZIF-8: same as in Example 1;

[0102] S2, preparation of mixed solution: same as in Example 1;

[0103] Preparation of S3, ZIF-8 / PEN composite honeycomb membrane

[0104] The PVP K30 / ZIF-8 / PEN / Pluronic F-127 mixed solution obtained in step S2 is poured onto a glass plate, and a 250 μm uniform liquid film is scraped using a wet film preparation device. The glass plate and the liquid film on its surface are then immersed in a coagulation bath, wherein the coagulation bath contains 2000 ml of deionized water. After the liquid film is converted into a solid film, it is peeled off from the glass plate, and the film is immersed in the coagulation bath for 36 hours. The film is then placed in a vacuum oven at 50° C. and dried for 8 hours. The film is then naturally cooled to room temperature to obtain a ZIF-8 / PEN composite honeycomb porous film.

[0105] Comparative Example 2

[0106] The preparation method of the ZIF-8 / PEN composite honeycomb porous film provided in this comparative example comprises the following steps:

[0107] S1. Take 10 ml of N-methylpyrrolidone and perform ultrasonic dispersion for 2 hours; then add 0.9 g of PEN and 0.1 g of triblock copolymer F-127 (Pluronic F-127), place the glass bottle containing the mixed solution on a magnetic heating stirrer, heat and stir at 60° C. for 1 hour, turn off the heating, and stir at room temperature for 30 minutes to obtain a PEN / Pluronic F-127 mixed solution;

[0108] Preparation of S2 and PEN composite honeycomb membrane

[0109] The PEN / Pluronic F-127 mixed solution obtained in step S1 was poured onto a glass plate, and a 250 μm uniform liquid film was scraped using a wet film preparation device. The glass plate and the liquid film on its surface were then immersed in a coagulation bath, wherein the ratio of the coagulation bath was 1400 ml of deionized water and 600 ml of ethanol. After the liquid film was converted into a solid film, it was peeled off from the glass plate and continued to be immersed in the coagulation bath for 36 hours. It was then placed in a vacuum oven at 50°C and dried for 8 hours, and naturally cooled to room temperature to obtain a ZIF-8 / PEN composite honeycomb porous film.

[0110] The performance of each thin film material prepared in the above embodiments and comparative examples was verified.

[0111] Test 1

[0112] Test samples: ZIF-8 / PEN composite honeycomb films prepared in Example 1, Example 4, and Example 7.

[0113] Test process: The above test samples were subjected to thickness test and film cross-section SEM microstructure test. The microstructure diagram is as follows: Figure 1 shown.

[0114] Thickness tests found that the thickness of the ZIF-8 composite honeycomb film is about 0.25 mm.

[0115] See also Figure 1 A is the cross-sectional structure of the ZIF-8 / PEN composite honeycomb film prepared in Example 1. It can be seen from the figure that the entire cross-sectional structure of the film is composed of honeycomb pores with an average size of 4.9 μm, and the ZIF-8 attached to the surface is uniformly dispersed in the PEN honeycomb pore skeleton; B is the cross-sectional structure of the ZIF-8 / PEN composite honeycomb film prepared in Example 4; it can be seen from the figure that the entire cross-sectional structure of the film is composed of a finger-like honeycomb pore structure; C is the cross-sectional structure of the ZIF-8 / PEN composite honeycomb film prepared in Example 7; it can be seen from the figure that the entire cross-sectional structure of the film is composed of a finger-like honeycomb pore structure, and the arrangement is more regular and uniform.

[0116] Test 2

[0117] Test sample: ZIF-8 / PEN composite honeycomb porous film prepared in Examples 1 to 10.

[0118] Test method: The conventional method of measuring the dielectric constant of existing films was used to measure the dielectric constant (k) of each group of ZIF-8 / PEN composite honeycomb films. Figure 2 As shown in Table 1, Figure 2 In Example 7 to Example 9, the mass fraction of ZIF-8 is 10%, 15%, and 20%, respectively, and all are in a 30% (v / v) ethanol bath, expressed as Fe3.

[0119] Table 1 Dielectric constants of each group of ZIF-8 composite honeycomb films

[0120]

[0121] from Figure 2 As shown in Table 1, in an ethanol solution with a volume concentration of 30% (v / v), as the mass fraction of ZIF-8 increases, the dielectric constant of the composite material shows a significant downward trend. Specifically, when the mass fraction of ZIF-8 increases from 0% (marked as F0) to 20% (marked as F 20 ), the dielectric constant dropped from 1.81 to 1.36; comparing the effects of different coagulants on the dielectric constant, the results showed that the dielectric constant of the composite material obtained using ethanol as a coagulant was higher than that of the composite material prepared in ethanol solutions with a volume concentration of 20% (v / v) and 30% (v / v).

[0122] Test 3

[0123] Test sample: ZIF-8 composite honeycomb porous film prepared in Examples 1 to 10.

[0124] Test method: The existing conventional method was used to test the mechanical properties of each group of ZIF-8 composite honeycomb porous films, such as tensile strength and elongation at break. The test results are shown in Table 2.

[0125] Table 2 Mechanical properties of each group of ZIF-8 composite honeycomb films

[0126] Tensile strength(MPa) Elongation at break (%) Example 1 11.2 87.9 Example 2 10.2 112.3 Example 3 8.3 108.0 Example 4 10.9 75.7 Example 5 8.6 105.4 Example 6 7.2 110.0 Example 7 10.7 70.4 Example 8 10.0 108.7 Example 9 6.8 94.1 Comparative Example 1 6.1 47.2 Comparative Example 2 12.0 58.1

[0127] It can be seen from Table 2 that the mechanical properties and toughness of the ZIF-8 composite honeycomb porous film obtained in an ethanol bath are better than those of the ZIF-8 composite honeycomb porous film obtained in a 20% (v / v) ethanol bath and a 30% (v / v) ethanol bath. The tensile strength and elongation at break of the film in the water bath are the lowest, which is the worst among all samples. With the increase of ZIF-8 precursor, the tensile strength of the ZIF-8 composite honeycomb porous film shows a downward trend. In a 30% (v / v) ethanol bath, the tensile strength decreases from 12.0 MPa of F0 to 6.8 MPa of F20, and the elongation at break increases from 58.1 of F0 to 108.7 of F15, and then decreases to 94.1 of F20.

[0128] Comprehensively considering that when a 30% (v / v) ethanol bath is used and the content of ZIF-8 is controlled at 15wt%, the obtained ZIF-8 / PEN composite honeycomb porous film achieves the best balance in various aspects of performance. Therefore, the conditions used in Example 8 provide an effective technical solution for preparing a ZIF-8 / PEN composite honeycomb porous film with comprehensive optimal performance.

[0129] Through the above test, it was found that the film material prepared using water as a coagulation bath (Comparative Example 1) can obtain the lowest dielectric constant of 1.25, but the mechanical properties of the film material are the worst among all samples; in addition, the film material without ZIF-8 (Comparative Example 2) has high tensile strength, but poor elongation at break; and its dielectric constant is 1.81, the highest value among all samples. The film material prepared by the present invention, when the dielectric constant value is 1.39, has a tensile strength of up to 10.0MPa and an elongation at break of up to 108.7%, and has excellent flexibility, dielectric properties and mechanical properties, which opens up a new way for the preparation and application of flexible ultra-low dielectric materials.

[0130] See also Figure 3 , fold the prepared film repeatedly into the shape of a boat ( Figure 3 left), and then unfold it and lay it out on the desktop ( Figure 3 Right side). It can be seen that the surface of the film is intact and not damaged after multiple foldings, which indicates that the film prepared by the present invention has good flexibility and can be folded multiple times without breaking.

[0131] Obviously, the above embodiments are only for the purpose of clearly illustrating the technical solution of the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications based on the above description of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for preparing a ZIF-8 / PEN composite honeycomb porous film, characterized in that: The following steps are involved: S1. Preparation of PVP K30 / ZIF-8 Take Zn(NO3)2·6H2O, polyvinyl pyrrolidone, 2-methylimidazole and a polar solvent, and obtain powdered PVP K30 / ZIF-8 by a step-by-step mixing method; the mass volume ratio of the Zn(NO3)2·6H2O, polyvinyl pyrrolidone, 2-methylimidazole and the polar solvent is (2-3) g: 1 g: (3-6) g: 200 ml; S2. Preparation of mixed solution The PVP K30 / ZIF-8 prepared in step S1 is dispersed in N-methylpyrrolidone, and after ultrasonic treatment, poly(arylene ether nitrile) and triblock copolymer nonionic surfactant are added in sequence, and heated and stirred at room temperature to obtain a mixed solution; the mass ratio of the PVP K30 / ZIF-8, poly(arylene ether nitrile) and triblock copolymer nonionic surfactant is (10-20):100:10; Preparation of S3, ZIF-8 / PEN composite honeycomb film The mixed solution obtained in step S2 is poured onto a glass plate, and a uniform liquid film with a thickness of 250 μm is scraped out, which is placed in a coagulation bath to form a solid film, and then allowed to stand and dry to obtain a ZIF-8 / PEN composite honeycomb porous film.

2. The method for preparing the ZIF-8 / PEN composite honeycomb porous film according to claim 1, characterized in that: In step S1, the step-by-step mixing method is specifically: S1.

1. Dissolve Zn(NO3)2·6H2O and polyvinyl pyrrolidone in a polar solvent to obtain solution A; in every 10 ml of solution A, the mass ratio of Zn(NO3)2·6H2O to polyvinyl pyrrolidone is (4-6):1; S1.2, dissolving 2-methylimidazole and polyvinylpyrrolidone in a polar solvent to obtain a solution B; in every 10 ml of solution B, the mass ratio of 2-methylimidazole to polyvinylpyrrolidone is (6-12):1; S1.3, after mixing solution A and solution B, stirring and standing to obtain ZIF-8 crystals; and then washing and drying to obtain powdered PVP K30 / ZIF-8.

3. The method for preparing the ZIF-8 / PEN composite honeycomb porous film according to claim 2, characterized in that: In the step S1.3, the stirring time is 1 h to 2 h, the standing time is 12 h to 36 h, the washing is 3 to 5 times, the drying temperature is 20° C. to 40° C., and the drying time is 4 h to 8 h.

4. The method for preparing the ZIF-8 / PEN composite honeycomb porous film according to claim 1, characterized in that: The polar solvent is any one of methanol, water and N,N-dimethylformamide; the triblock copolymer nonionic surfactant is any one of triblock copolymer Pluronic F-98, triblock copolymer Pluronic F-108 and triblock copolymer Pluronic F-127; the coagulation bath is an ethanol solution, and the volume fraction of ethanol in the ethanol solution is 20% to 100%.

5. The method for preparing the ZIF-8 / PEN composite honeycomb porous film according to claim 1, characterized in that: In step S2, the ultrasonic time is 1h to 2h, the heating stirring speed and the room temperature stirring speed are both 100r / min to 300r / min, the stirring temperature is 30 to 80°C, the heating stirring time is 1h to 2h, and the room temperature stirring time is 30min to 60min.

6. The method for preparing the ZIF-8 / PEN composite honeycomb porous film according to claim 1, characterized in that: In the step S3, the standing time is 12 hours to 36 hours, the drying temperature is 20° C. to 40° C., and the drying time is 6 hours to 8 hours.

7. A ZIF-8 / PEN composite honeycomb porous film prepared by the method for preparing a ZIF-8 / PEN composite honeycomb porous film according to claim 1.

8. The ZIF-8 / PEN composite honeycomb film according to claim 7, characterized in that: The ZIF-8 / PEN composite honeycomb porous film is a honeycomb structure or a finger-shaped porous structure, the pore size is 4.9 μm to 6.2 μm, and the thickness is 0.25±0.05 mm.

9. The ZIF-8 / PEN composite honeycomb film according to claim 7, characterized in that: The ZIF-8 / PEN composite honeycomb porous film has a lowest dielectric constant of 1.39, a highest tensile strength of 10 MPa, and a highest elongation at break of 108.3%.

10. Application of the ZIF-8 / PEN composite honeycomb film as claimed in claim 9 in flexible ultra-low dielectric materials.

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