Polyimide film cross-linked by aminated quantum dots and preparation method thereof

Abstract

The invention provides an aminated quantum dot cross-linked polyimide film and a preparation method thereof, and is characterized in that the preparation method comprises the following steps: (1) respectively dissolving dianhydride and diamine in a solvent; (2) uniformly mixing the two solutions; (3) dissolving the aminated quantum dots, and adding the aminated quantum dots into the solution obtained in the step (2); (4) uniformly dispensing the solution in the step (3) on a clean glass sheet, and carrying out thermal imidization to obtain a PI hybrid film; the addition of the aminated quantum dots aims to reduce the conductivity loss by introducing trap points and inhibiting the synergistic effect of polymer chain movement, and the covalent interaction enhances the structure of the polymer, significantly improves the thermal stability of the polymer, and effectively reduces the diffusion velocity of charges in the polymer, thereby inhibiting charge transfer and optimizing the high-temperature performance; expression of the hybrid film added with the aminated quantum dots proves that the hybrid film has huge potential in high-temperature energy storage application, and a new research direction is provided for development of efficient capacitor materials.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature energy storage thin films, and particularly relates to a polyimide thin film crosslinked by amino-functionalized quantum dots and a preparation method thereof. Background Art

[0002] Polyimide materials have high molecular structure rigidity and strong intermolecular forces, and thus have excellent heat resistance, mechanical properties, dielectric properties, corrosion resistance, radiation resistance, etc., and have broad application prospects in the fields of aerospace, electrical and electronics, etc. However, under high-temperature and high-electric-field conditions, polyimide dielectric materials are difficult to meet the requirements of high energy density and stability. Therefore, developing dielectric polyimide thin film materials with high temperature and high energy density has become a key problem to be solved urgently in the field of thin film capacitors. Summary of the Invention

[0003] Aiming at the problems existing in the prior art, a new method is proposed, that is, by covalently bonding A-QDs to the PI matrix to form a crosslinked network to inhibit the electron transport characteristics of polymer dielectric materials. After introducing quantum dots as crosslinking points, their quantum confinement effect can form charge traps to limit charge transport. At the same time, the crosslinking effect inhibits the movement of polymer segments and reduces the mobility of electrons in the polymer backbone, thereby significantly enhancing the insulation performance of the hybrid material.

[0004] To achieve the above technology, the present invention provides a polyimide thin film crosslinked by amino-functionalized quantum dots and a preparation method thereof, which is characterized in that the preparation method is as follows:

[0005] (1) First, dissolve the dianhydride in a solvent to obtain a mixed solution 1, and dissolve the diamine in a solvent to obtain a mixed solution 2;

[0006] (2) Further mix and stir the mixed solution 1 and the mixed solution 2 for 12 hours to obtain a mixed solution 3;

[0007] (3) Then, dissolve the amino-functionalized quantum dots (A-QDs) in a solvent and stir for 2 hours to obtain a mixed solution 4;

[0008] (4) Subsequently, gradually add the mixed solution 4 to the mixed solution 3 to obtain a mixed solution 5, and continuously stir the mixed solution 5 for 24 hours to make it uniformly dispersed;

[0009] (5) Then, uniformly drop the obtained mixed solution 5 onto a clean glass slide;

[0010] (6) Then, perform thermal imidization treatment on the mixed solution 5 on the glass slide;

[0011] (7) After the thermal imidization is completed, the mixed solution 5 is formed into a film on a glass slide. The glass slide is immersed in deionized water, and the film is peeled off from the glass slide and dried in a vacuum oven to completely remove the residual moisture, obtaining a film.

[0012] Further, the dianhydride is 4,4'-diaminodiphenylmethane (MDA).

[0013] Further, the diamine is 4,4'-oxybisphthalic anhydride (ODPA).

[0014] Further, the amino-functionalized quantum dots (A-QDs) are any one of A-CQDs, A-BNQDs, and A-CdSeQDs, all from Xi'an Ruixi Biotechnology.

[0015] Further, the solid content of the amino-functionalized quantum dots (A-QDs) in the mixed solution 4 is 50%.

[0016] Further, the mixed solution 4 accounts for 0.2 - 2% of the volume fraction of the mixed solution 3.

[0017] Further, the solvents are all N-methylpyrrolidone, and the molar ratio of the dianhydride to the diamine monomer is 1:1.

[0018] Further, the thermal imidization process is as follows: first, vacuum dry at 80 °C for 12 hours to completely remove the solvent, and then heat at 150 °C, 200 °C, and 250 °C for 1 hour each;

[0019] Further, the film thickness is 12 μm.

[0020] Further, a polyimide film crosslinked by amino-functionalized quantum dots.

[0021] The beneficial effects of the present invention are as follows: To effectively reduce the conductance loss of polymers at high temperatures, the present invention uses amino-functionalized quantum dots (A-QDs) as crosslinking agents to synthesize composite films through in-situ polymerization, aiming to reduce the conductance loss through the synergistic effects of introducing trap sites and inhibiting the movement of polymer chains. The NH2 groups on the A-QDs promote covalent bonding with the PI matrix, forming a crosslinked network structure. This covalent interaction enhances the structure of the polymer, significantly improves its thermal stability, and effectively reduces the diffusion rate of charges in the polymer, thereby inhibiting charge transfer and optimizing the high-temperature performance. In addition, the size of the quantum dots is close to the exciton Bohr radius, exhibiting a significant quantum confinement effect, which can effectively capture free charges and prevent their free movement. Therefore, after introducing quantum dots as polymer crosslinking points, the quantum confinement effect can generate trap-limited charge transport, and can also inhibit the movement of polymer segments by forming crosslinking points, reducing the mobility of electrons in the polymer backbone, thereby enhancing the insulation performance of the composite polymer. Introducing traps helps to limit charge transport, while inhibiting the movement of polymer chains can reduce the migration path and speed of charges, which is crucial for improving the high-temperature stability and electrical properties of polymers. Combining these two strategies not only improves the electrical properties of polymers at high temperatures, but also improves their long-term stability as capacitive energy storage materials, providing a promising path for large-scale production of polymer dielectric films. Specific embodiments

[0022] Comparative example 1

[0023] A polyimide film and its preparation method are as follows:

[0024] (1) First, dissolve 0.1 mmol of dianhydride 4,4'-diaminodiphenylmethane (MDA) in 5 mL of N-methylpyrrolidone to obtain a mixed solution 1, and dissolve 0.1 mmol of diamine 4,4'-oxybisphthalic anhydride (ODPA) in 5 mL of N-methylpyrrolidone to obtain a mixed solution 2;

[0025] (2) Further mix and stir the mixed solution 1 and the mixed solution 2 for 12 hours to obtain a solution 3;

[0026] (3) Then, uniformly drop the mixed solution 3 onto a clean glass slide;

[0027] (4) Then, perform thermal imidization treatment on the mixed solution 3 on the glass slide: first, vacuum dry it at 80 °C for 12 hours to thoroughly remove the solvent, and then heat it at 150 °C, 200 °C, and 250 °C for 1 hour each;

[0028] (5) After the thermal imidization is completed, the mixed solution 3 is formed into a film on a glass slide. The glass slide is immersed in deionized water, and the film is peeled off from the glass slide and dried in a vacuum oven to completely remove the residual moisture, obtaining a 12-μm film.

[0029] Example 1

[0030] A general polyimide film and its preparation method are as follows:

[0031] (1) First, dissolve 0.1 mmol of dianhydride 4,4'-diaminodiphenylmethane (MDA) in 5 mL of N-methylpyrrolidone to obtain a mixed solution 1, and dissolve 0.1 mmol of diamine 4,4'-oxydiphthalic anhydride (ODPA) in 5 mL of N-methylpyrrolidone to obtain a mixed solution 2;

[0032] (2) Further mix the mixed solution 1 and the mixed solution 2 and stir for 12 hours to obtain a solution 3;

[0033] (3) Then, dissolve A-BNQDs in N-methylpyrrolidone and stir for 2 hours to obtain a solution 4 with a solid content of 50%;

[0034] (4) Subsequently, gradually add the mixed solution 4 to the mixed solution 3. The mixed solution 4 is 0.2% of the volume content of the mixed solution 3 to obtain a mixed solution 5, and the mixed solution 5 is continuously stirred for 24 hours to make it evenly dispersed;

[0035] (5) Then, evenly drip the obtained mixed solution 5 onto a clean glass slide;

[0036] (6) Then, perform thermal imidization treatment on the mixed solution 5 on the glass slide: first, vacuum dry at 80°C for 12 hours to completely remove the solvent, and then heat at 150°C, 200°C, and 250°C for 1 hour each;

[0037] (7) After the thermal imidization is completed, the mixed solution 5 is formed into a film on a glass slide. The glass slide is immersed in deionized water, and the film is peeled off from the glass slide and dried in a vacuum oven to completely remove the residual moisture, obtaining a 12-μm film.

[0038] Example 2

[0039] A general polyimide film and its preparation method are as follows:

[0040] (1) First, dissolve 0.1 mmol of dianhydride 4,4'-diaminodiphenylmethane (MDA) in 5 mL of N-methylpyrrolidone to obtain a mixed solution 1, and dissolve 0.1 mmol of diamine 4,4'-oxydiphthalic anhydride (ODPA) in 5 mL of N-methylpyrrolidone to obtain a mixed solution 2;

[0041] (2) Further mix the mixed solution 1 and the mixed solution 2 and stir for 12 hours to obtain solution 3;

[0042] (3) Then, dissolve A-CQDs in N-methylpyrrolidone and stir for 2 hours to obtain solution 4 with a solid content of 50%;

[0043] (4) Subsequently, gradually add the mixed solution 4 to the mixed solution 3. The mixed solution 4 is 0.2% of the volume content of the mixed solution 3 to obtain the mixed solution 5. The mixed solution 5 is continuously stirred for 24 hours to make it evenly dispersed;

[0044] (5) Then, evenly drop-coat the obtained mixed solution 5 onto a clean glass slide;

[0045] (6) Then, perform thermal imidization treatment on the mixed solution 5 on the glass slide: first, vacuum dry at 80 °C for 12 hours to completely remove the solvent, and then heat at 150 °C, 200 °C, and 250 °C for 1 hour each;

[0046] (7) After the thermal imidization is completed, the mixed solution 5 forms a film on the glass slide. Immerse the glass slide in deionized water, peel the film from the glass slide, and dry it in a vacuum oven to completely remove the residual moisture to obtain a 12-μm film.

[0047] Example 3

[0048] A polyimide film and a preparation method thereof, the preparation method is as follows:

[0049] (1) First, dissolve 0.1 mmol of dianhydride 4,4'-diaminodiphenylmethane (MDA) in 5 mL of N-methylpyrrolidone to obtain the mixed solution 1, and dissolve 0.1 mmol of diamine 4,4'-oxybisphthalic anhydride (ODPA) in 5 mL of N-methylpyrrolidone to obtain the mixed solution 2;

[0050] (2) Further mix the mixed solution 1 and the mixed solution 2 and stir for 12 hours to obtain solution 3;

[0051] (3) Then, dissolve A-CdSeQDs in N-methylpyrrolidone and stir for 2 hours to obtain solution 4 with a solid content of 50%;

[0052] (4) Subsequently, gradually add the mixed solution 4 to the mixed solution 3. The mixed solution 4 is 0.2% of the volume content of the mixed solution 3 to obtain the mixed solution 5. The mixed solution 5 is continuously stirred for 24 hours to make it evenly dispersed;

[0053] (5) Then, evenly drop-coat the obtained mixed solution 5 onto a clean glass slide;

[0054] (6) Then, perform thermal imidization on the mixed solution 5 on the glass slide: first, dry it in vacuum at 80 °C for 12 hours to completely remove the solvent, and then heat it at 150 °C, 200 °C, and 250 °C for 1 hour each;

[0055] (7) After the thermal imidization is completed, the mixed solution 5 forms a film on the glass slide. Immerse the glass slide in deionized water, peel the film from the glass slide, and dry it in a vacuum oven to completely remove the residual moisture, obtaining a 12-μm film.

[0056] Example 4

[0057] A polyimide film and its preparation method are as follows:

[0058] (1) First, dissolve 0.1 mmol of dianhydride 4,4'-diaminodiphenylmethane (MDA) in 5 mL of N-methylpyrrolidone to obtain a mixed solution 1, and dissolve 0.1 mmol of diamine 4,4'-oxybisphthalic anhydride (ODPA) in 5 mL of N-methylpyrrolidone to obtain a mixed solution 2;

[0059] (2) Further mix and stir the mixed solution 1 and the mixed solution 2 for 12 hours to obtain a solution 3;

[0060] (3) Then, dissolve A-BNQDs in N-methylpyrrolidone and stir for 2 hours to obtain a solution 4 with a solid content of 50%;

[0061] (4) Subsequently, gradually add the mixed solution 4 to the mixed solution 3. The mixed solution 4 is 0.6% of the volume of the mixed solution 3 to obtain a mixed solution 5, and the mixed solution 5 is continuously stirred for 24 hours to make it evenly dispersed;

[0062] (5) Then, evenly drop the obtained mixed solution 5 onto a clean glass slide;

[0063] (6) Then, perform thermal imidization on the mixed solution 5 on the glass slide: first, dry it in vacuum at 80 °C for 12 hours to completely remove the solvent, and then heat it at 150 °C, 200 °C, and 250 °C for 1 hour each;

[0064] (7) After the thermal imidization is completed, the mixed solution 5 forms a film on the glass slide. Immerse the glass slide in deionized water, peel the film from the glass slide, and dry it in a vacuum oven to completely remove the residual moisture, obtaining a 12-μm film.

[0065] Example 5

[0066] A polyimide film and its preparation method are as follows:

[0067] (1) First, dissolve 0.1 mmol of dianhydride 4,4'-diaminodiphenylmethane (MDA) in 5 mL of N-methylpyrrolidone to obtain mixed solution 1, and dissolve 0.1 mmol of diamine 4,4'-oxydiphthalic anhydride (ODPA) in 5 mL of N-methylpyrrolidone to obtain mixed solution 2;

[0068] (2) Further mix and stir mixed solution 1 and mixed solution 2 for 12 hours to obtain solution 3;

[0069] (3) Then, dissolve A-BNQDs in N-methylpyrrolidone and stir for 2 hours to obtain solution 4 with a solid content of 50%;

[0070] (4) Subsequently, gradually add mixed solution 4 to mixed solution 3. Mixed solution 4 is 1.0% by volume of mixed solution 3 to obtain mixed solution 5, and continuously stir mixed solution 5 for 24 hours to make it evenly dispersed;

[0071] (5) Next, evenly drop the obtained mixed solution 5 onto a clean glass slide;

[0072] (6) Then, perform thermal imidization treatment on the mixed solution 5 on the glass slide: first, vacuum dry at 80 °C for 12 hours to completely remove the solvent, and then heat at 150 °C, 200 °C, and 250 °C for 1 hour each;

[0073] (7) After the thermal imidization is completed, the mixed solution 5 forms a film on the glass slide. Immerse the glass slide in deionized water, peel the film from the glass slide, and dry it in a vacuum oven to completely remove the residual moisture to obtain a 12-μm film.

[0074] Example 6

[0075] A polyimide film and its preparation method are as follows:

[0076] (1) First, dissolve 0.1 mmol of dianhydride 4,4'-diaminodiphenylmethane (MDA) in 5 mL of N-methylpyrrolidone to obtain mixed solution 1, and dissolve 0.1 mmol of diamine 4,4'-oxydiphthalic anhydride (ODPA) in 5 mL of N-methylpyrrolidone to obtain mixed solution 2;

[0077] (2) Further mix and stir mixed solution 1 and mixed solution 2 for 12 hours to obtain solution 3;

[0078] (3) Then, dissolve A-BNQDs in N-methylpyrrolidone and stir for 2 hours to obtain solution 4 with a solid content of 50%;

[0079] (4) Subsequently, the mixed solution 4 was gradually added to the mixed solution 3. The mixed solution 4 was 1.6% of the volume of the mixed solution 3, and the mixed solution 5 was obtained. The mixed solution 5 was continuously stirred for 24 hours to make it evenly dispersed;

[0080] (5) Then, the obtained mixed solution 5 was evenly drop-coated on a clean glass slide;

[0081] (6) Then, thermal imidization treatment was carried out on the mixed solution 5 on the glass slide: first, it was vacuum-dried at 80 °C for 12 hours to completely remove the solvent, and then it was heated at 150 °C, 200 °C, and 250 °C for 1 hour respectively;

[0082] (7) After the thermal imidization was completed, the mixed solution 5 formed a film on the glass slide. The glass slide was immersed in deionized water, and the film was peeled off from the glass slide and dried in a vacuum oven to completely remove the residual moisture, obtaining a 12-μm film.

[0083] Example 7

[0084] A polyimide film and its preparation method are as follows:

[0085] (1) First, 0.1 mmol of dianhydride 4,4'-diaminodiphenylmethane (MDA) was dissolved in 5 mL of N-methylpyrrolidone to obtain a mixed solution 1, and 0.1 mmol of diamine 4,4'-oxybisphthalic anhydride (ODPA) was dissolved in 5 mL of N-methylpyrrolidone to obtain a mixed solution 2;

[0086] (2) The mixed solution 1 and the mixed solution 2 were further mixed and stirred for 12 hours to obtain a solution 3;

[0087] (3) Then, A-BNQDs was dissolved in N-methylpyrrolidone and stirred for 2 hours to obtain a solution 4 with a solid content of 50%;

[0088] (4) Subsequently, the mixed solution 4 was gradually added to the mixed solution 3. The mixed solution 4 was 2.0% of the volume of the mixed solution 3, and the mixed solution 5 was obtained. The mixed solution 5 was continuously stirred for 24 hours to make it evenly dispersed;

[0089] (5) Then, the obtained mixed solution 5 was evenly drop-coated on a clean glass slide;

[0090] (6) Then, thermal imidization treatment was carried out on the mixed solution 5 on the glass slide: first, it was vacuum-dried at 80 °C for 12 hours to completely remove the solvent, and then it was heated at 150 °C, 200 °C, and 250 °C for 1 hour respectively;

[0091] (7) After the thermal imidization is completed, the mixed solution 5 is formed into a film on a glass slide. The glass slide is immersed in deionized water, and the film is peeled off from the glass slide and dried in a vacuum oven to completely remove the residual moisture, obtaining a 12-μm film.

[0092] The above comparative examples and examples were tested, and the test results are shown in Table 1:

[0093] 1. The steps for testing the dielectric properties of the samples are as follows: First, gold electrodes with a diameter of 10 mm and a thickness of 60 nm are sputtered on both sides of the film. Subsequently, a broadband dielectric spectrometer (Novocontrol Concept 80) and a Quatro-Cryosystem temperature control system are used to test the dielectric spectrum of the samples at 10 2 ~10 6 Hz, and at the same time, by precisely controlling the oven temperature in the range of 25 - 250 °C, the dielectric constant and dielectric loss of the samples are obtained.

[0094] 2. To evaluate the effect of the samples in terms of high-temperature insulation performance, a TREK 610C amplifier is used to measure the breakdown field strength of the samples, that is, a voltage is applied to the samples at a DC boost rate of 500 V / s until electrical breakdown occurs. To ensure the reliability of the results, each sample needs to be tested at least 20 times. The test results are analyzed using the two-parameter Weibull statistical method to determine the high-temperature breakdown strength (Eb) of the samples. A higher Eb means that the dielectric polymer has a higher breakdown strength and stability, which means that the samples have higher breakdown reliability at high temperatures and can maintain stable insulation performance even under extreme conditions.

[0095] 3. To prove the high-temperature energy storage performance of the samples, the samples are subjected to an electric displacement - electric field strength cyclic test at a temperature of 200 °C, a frequency of 100 Hz, and an electric field of 650 MV / m. The hysteresis loop of the samples is integrated to obtain the discharge energy density of the samples. The higher the discharge energy density, the better the high-temperature energy storage performance.

[0096] Table 1

[0097]

[0098] From the comparison data of the comparative examples and examples, it can be seen that compared with pure PI, after adding amino-functionalized quantum dots to crosslink PI, the dielectric constant of PI is improved, the high-temperature energy storage performance is improved, and the high-temperature insulation performance is improved, so as to expand the application of polyimide as a high-temperature dielectric material.

Claims

1. A polyimide film crosslinked by aminated quantum dots and a preparation method thereof, characterized in that, The preparation method is as follows: (1) First, dissolve the dianhydride in a solvent to obtain mixed solution 1, and dissolve the diamine in a solvent to obtain mixed solution 2; (2) Further mix mixed solution 1 and mixed solution 2 and stir for 12 hours to obtain mixed solution 3; (3) Then, dissolve the amino-functionalized quantum dots (A-QDs) in a solvent and stir for 2 hours to obtain mixed solution 4; (4) Subsequently, gradually add mixed solution 4 to mixed solution 3 to obtain mixed solution 5, and continuously stir mixed solution 5 for 24 hours to make it evenly dispersed; (5) Next, evenly drop the obtained mixed solution 5 onto a clean glass slide; (6) Then, perform thermal imidization treatment on the mixed solution 5 on the glass slide; (7) After the thermal imidization is completed, a film is formed from mixed solution 5 on the glass slide. Immerse the glass slide in deionized water, peel the film from the glass slide, and dry it in a vacuum oven to completely remove the residual moisture to obtain the film.

2. The polyimide film crosslinked by aminated quantum dots according to claim 1 and its preparation method are characterized in that, The dianhydride is 4,4'-diaminodiphenylmethane (MDA).

3. A polyimide film crosslinked by aminated quantum dots according to claim 2 and a preparation method thereof, characterized in that, The diamine is 4,4'-oxybisphthalic anhydride (ODPA).

4. A polyimide film crosslinked by aminated quantum dots according to claim 1 and a preparation method thereof, characterized in that, The amino-functionalized quantum dots (A-QDs) are any one of A-CQDs, A-BNQDs, and A-CdSeQDs, all from Xi'an Ruixi Biotechnology Co., Ltd.

5. A polyimide film crosslinked by aminated quantum dots according to claim 1 and a preparation method thereof, characterized in that, The solid content of the amino-functionalized quantum dots (A-QDs) in mixed solution 4 is 50%.

6. The polyimide film crosslinked by aminated quantum dots according to claim 5 and its preparation method, characterized in that, Mixed solution 4 accounts for 0.2 - 2% of the volume fraction of mixed solution 3.

7. A polyimide film crosslinked by aminated quantum dots according to claim 1 and its preparation method, characterized in that, The solvent is N-methylpyrrolidone, and the molar ratio of the dianhydride to the diamine monomer is 1:

1.

8. A polyimide film crosslinked by aminated quantum dots according to claim 1 and a preparation method thereof, characterized in that, The thermal imidization treatment process is as follows: First, vacuum dry at 80°C for 12 hours to completely remove the solvent, and then heat at 150°C, 200°C, and 250°C for 1 hour each.

9. The polyimide film crosslinked by aminated quantum dots and its preparation method according to claim 1, characterized in that, The thickness of the film is 12 μm.

10. A polyimide film crosslinked by amino-functionalized quantum dots.

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