CN111116911B - A kind of polyimide containing benzoxazole and carbazole structure and its preparation method and application - Google Patents

Abstract

The invention discloses polyimide containing benzoxazole and carbazole structures and a preparation method and application thereof, starting from dihalogenated carbazole, grafting a benzoxazole-containing structural unit by using active hydrogen in monomer carbazole, preparing a novel functional diamine monomer with benzoxazole and carbazole structures through Suzuki reaction or direct liquid ammonia ammoniation, and then using the diamine compound for synthesizing high-performance and functional polymers such as novel polyimide, polyamide, polyesterimide and the like; the polyimide material synthesized by the diamine monomer has high thermal stability, obvious fluorescence characteristic and high luminous intensity.

Description

A kind of polyimide containing benzoxazole and carbazole structure and its preparation method and application

technical field

The invention relates to the technical field of material science, in particular to a polyimide containing benzoxazole and carbazole structures and a preparation method and application thereof.

Background technique

Polyimide is a class of high-performance polymers containing imide rings on the main chain. It is one of the best heat-resistant varieties of engineering plastics that have been industrialized at present. It has outstanding properties unmatched by other materials, such as high Mechanical strength, high and low temperature resistance, chemical corrosion resistance, good dimensional stability and excellent film-forming properties, etc., so it has a wide range of applications in aerospace, microelectronics, military industry, liquid crystal display and other fields. On the other hand, with the advancement of display technology, organic light-emitting diodes have become the most popular in the past decade due to their advantages of active light emission, full-color display, low power consumption, low startup voltage, high brightness, fast response, simple processing technology and low cost. One of the research hotspots in the field of organic optoelectronics. Compared with organic small-molecule light-emitting materials, polymer light-emitting materials can be formed into large-area films by various techniques such as spin coating, dipping, and ink-jet printing to prepare flexible devices with simple structures. The cost is low, and light-emitting polymers can be designed. It has strong properties, and its luminescent color can be adjusted by changing the molecular structure. However, the preparation and purification process of polymer luminescent materials are complicated, the colorization is difficult and the lifespan is short, which are the bottlenecks restricting their application in the display field. Especially in the process of device fabrication, these organic materials will undergo chemical changes such as oxidation and photodegradation. At the same time, due to their dimensional instability at high temperature and their easy crystallization, the stability and life of the device are seriously affected. Therefore, polyimide materials with excellent thermal stability can overcome the above-mentioned shortcomings of common organic materials and be applied in the field of PLED luminescent materials.

Most benzoxazole compounds have strong fluorescence, and some have laser properties. They are often used as fluorescent probes, fluorescent whitening agents, laser dyes in the near-ultraviolet band, and sensitizing dyes and supersensitizing dyes in photosensitive emulsions. agent. In recent years, because some of them have biological activity and can be used as bactericides, antiseptics and antitumor agents, such as CN103333131A, CN107778301A, etc., the research on them has become increasingly active. At present, there are few reports on the research of benzoxazole compounds in the field of polymer luminescence. Using their good electron transport ability and excellent fluorescence properties, the fluorescence properties of polyimide can be effectively improved through molecular structure design. and high luminous intensity.

In order to obtain high-efficiency luminescent polyimide, different functional groups are generally introduced into diamine monomers with excellent structural designability, which endow polyimide with unique optoelectronic properties. At present, polyimides with a certain photoluminescence efficiency generally adopt organic conjugated chromophores introduced into diamine or dianhydride monomers. Such as US 5777417, CN1371932 and JP2008297354 and so on. However, in this type of polyimide, there is still a strong interaction between the main chains, between the side groups or between the main chain and the side groups, the number of charge transfer complexes cannot be reduced, and the charge transfer effect is still strong.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention provides a polyimide containing benzoxazole and carbazole structures and a preparation method and application thereof. Starting from dihalogenated carbazoles, using active hydrogen in monomeric carbazole to graft benzoxazole-containing structural units to prepare novel functional dioxazoles with benzoxazole and carbazole structures through Suzuki reaction or direct liquid ammonia amination amine monomer, and then the diamine compound is used to synthesize high-performance and functional polymers such as new polyimide, polyamide, polyesterimide, etc.; the polyimide material synthesized from the obtained diamine monomer is thermally stable High performance, with obvious fluorescence characteristics and high luminous intensity.

One of the technical solutions of the present invention is a polyimide containing benzoxazole and carbazole structures, and the structural formula of the polyimide is as follows:

where n and m represent the degree of polymerization, n/m=1/99～100/0, X and W are tetravalent aromatic hydrocarbon groups or aliphatic hydrocarbon groups, Z is a divalent aromatic hydrocarbon group or aliphatic hydrocarbon group, and Y is One or two mixtures of the groups represented by the general structural formula Y-1 or Y-2:

Preferably, R ₁ , R ₂ , R ₃ and R ₄ in the general structural formula Y-1 or Y-2 are selected from any one of the following structural formulas:

Preferably, the preparation method of the group Y of the diamine compound containing carbazole and benzoxazole structure represented by the general structural formula Y-1 or Y-2 comprises the following steps:

(1) Utilize substituted p-fluorophenylboronic acid and 2-chlorobenzoxazole to couple through Suzuki reaction to obtain 2-substituted phenylbenzoxazole structure;

(2) utilizing the group containing the benzoxazole structure obtained in the active hydrogen grafting step (1) in the dihalogenated carbazole monomer carbazole;

(3) prepare diamine with the structure obtained in step (2) and p-aminophenylboronic acid or m-aminophenylboronic acid through Suzuki coupling reaction to obtain a class of benzoxazole and carboxylate as described in Y-1 or Y-2 A planar diamine with an azole structure.

Preferably, the X or W are the same or different, and are selected from one or more of the following tetravalent aromatic hydrocarbyl or aliphatic hydrocarbyl structural formulas:

Preferably, described Z is selected from any one of the following divalent aromatic hydrocarbon group or aliphatic hydrocarbon group structural formula:

The second technical solution of the present invention, the above-mentioned preparation method of the polyimide containing benzoxazole and carbazole structure, comprises the following steps: in argon or nitrogen atmosphere, the diamine monomer containing Y structure or The mixed diamine containing Y and Z structure and the dianhydride containing X structure or the mixed dianhydride containing X and W structure are dissolved in an aprotic polar organic solvent in a molar ratio of 1:(1～1.1), at -10 The reaction is stirred for 6 to 72 hours at °C to 40 °C to obtain a polyamic acid solution, and then imidized by thermal imidization or chemical imidization to obtain the polyimide.

Preferably, the total mass of the diamine monomer containing Y structure or the mixed diamine monomer containing Y and Z structure and the dianhydride monomer containing X structure or the mixed dianhydride monomer containing X and W structure accounts for the total mass of the reaction material. 5 to 50% of the mass.

Preferably, the aprotic polar organic solvent is selected from N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, and dimethyl sulfone , 1,4-dioxane, tetrahydrofuran, m-cresol, or a mixture of two or more.

Preferably, the preparation of polyimide by the thermal imidization method includes the following steps: placing the polyamic acid solution in a vacuum oven, performing foaming treatment, and after removing the bubbles, scraping the polyamic acid solution on a clean On the substrate, place the substrate in a high-temperature vacuum oven, and heat up according to the set program: from room temperature to 100 °C, hold at 100 °C ± 2 °C for 1 h, then heat up to 200 °C, and keep at 200 °C ± 2 °C 1h, then heat up to 300°C, hold at 300°C±2°C for 1h, then heat up to 370°C, hold at 370°C±2°C for 0.5h; The substrate is taken out and soaked in hot water at 80-100° C. to peel off the film, and vacuum-dried at 180° C. to remove residual solvent to obtain a polyimide film.

Preferably, the bubbling treatment time is 0.5-1 h, and the substrate is glass, copper, aluminum, iron or silicon.

Preferably, the chemical imidization method for preparing polyimide comprises the following steps:

(1) Add acetic anhydride and pyridine in the polyamic acid solution as dehydrating agent and catalyst respectively, so that the molar ratio of -COOH in the acetic anhydride and the polyamic acid solution is 10:1, and the molar ratio of acetic anhydride and pyridine is 5 : 2. Under the condition of ambient humidity lower than 40%, ambient temperature 0～30℃, and argon gas, stir for 8～15h, add the obtained solution dropwise to absolute ethanol or methanol solution for precipitation, filter and use excess The obtained polyimide fibers were then washed with distilled water, and then the obtained polyimide fibers were fully dried in a 150 ℃ vacuum oven to obtain polyimide powder materials;

(2) Dissolve the above-mentioned polyimide powder material in an aprotic polar organic solvent, place it in a vacuum oven at room temperature, and evacuate it to a vacuum for defoaming treatment. After the air bubbles are eliminated, the polyimide The solution is scraped on a clean substrate, and then the substrate is placed in a high-temperature vacuum oven, heated to 70-300° C. for drying, and a polyimide film can be obtained after cooling.

Preferably, the aprotic polar organic solvent is N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, dimethyl sulfone, 1 , One or more of 4-dioxane, tetrahydrofuran or m-cresol, the bubble extraction treatment time is 0.5-1h, and the substrate is glass, copper, aluminum, iron or silicon.

The third technical solution of the present invention is the application of the above-mentioned polyimide containing benzoxazole and carbazole structures in the preparation of light-emitting layer materials, photoluminescent materials and flexible electroluminescent devices in optical devices.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention adopts the polyimide material synthesized by the diamine compound containing carbazole and benzoxazole structure, because the diamine compound has a weak electron-withdrawing light-emitting element benzoxazole structure, can effectively reduce the charge transfer effect, and has Good thermal stability, so that the polyimide material synthesized with it as a monomer also has high thermal stability, obvious fluorescence characteristics and high luminous intensity, making it suitable for the preparation of light-emitting layer materials, light-emitting materials in optical devices. It can be widely used in electroluminescent materials and flexible electroluminescent devices, and solves the problem of polyimide in the prior art, and there is still a strong interaction between the main chains, between the side groups or between the main chain and the side groups. , the number of charge transfer complexes cannot be reduced, and the charge transfer effect is still a technical problem.

Description of drawings

Fig. 1 is the thermogravimetric analysis spectrogram of the polyimide prepared by Example 1;

Fig. 2 is the fluorescence spectrogram of the polyimide prepared in Example 1;

Fig. 3 is the infrared spectrogram of the polyimide prepared by Example 1;

Fig. 4 is the nuclear magnetic image of the diamine monomer prepared in Example 1;

Fig. 5 is the mass spectrum of the diamine monomer prepared in Example 1;

FIG. 6 is the infrared spectrum of the diamine monomer prepared in Example 1. FIG.

Detailed ways

The present invention is a polyimide containing benzoxazole and carbazole structures, which can be applied to the preparation of light-emitting layer materials, photoluminescent materials and flexible electroluminescent devices in optical equipment. one):

where n and m represent the degree of polymerization, n/m=1/99～100/0, X and W are tetravalent aromatic hydrocarbon groups or aliphatic hydrocarbon groups, Z is a divalent aromatic hydrocarbon group or aliphatic hydrocarbon group, and Y is One or two mixtures of the groups represented by the general structural formula Y-1 or Y-2:

Wherein, R ₁ , R ₂ , R ₃ and R ₄ in the general structural formula Y-1 or Y-2 are selected from any one of the following structural formulas:

Wherein, the preparation method of the group Y of the diamine compound containing carbazole and benzoxazole structure shown in general formula Y-1 or Y-2 comprises the following steps:

(1) Utilize substituted p-fluorophenylboronic acid and 2-chlorobenzoxazole to couple through Suzuki reaction to obtain 2-substituted phenylbenzoxazole structure, and its general structural formula is such as structural formula (two):

(2) using the active hydrogen grafting step (1) in the dihalogenated carbazole monomer carbazole to obtain a dihalogenated structure containing a carbazole benzoxazole structure, and its general structural formula is as structural formula (3);

where X can be fluorine, chlorine, bromine or iodine.

(3) prepare diamine by Suzuki coupling reaction with the dihalogenated structure obtained in step (2) and 4-aminophenylboronic acid or 3-aminophenylboronic acid, wherein, react with 4-aminophenylboronic acid to obtain a Y-1-containing structure Diamine monomer, as shown in structural formula (4), reacts with 3-aminophenylboronic acid to obtain a planar diamine monomer containing Y-2 structure, as shown in structural formula (5).

Wherein, described X or W are the same or different, and are selected from one or more of the following tetravalent aromatic hydrocarbon group or aliphatic hydrocarbon group structural formula:

Wherein, described Z is selected from any one in the following divalent aromatic hydrocarbon group or aliphatic hydrocarbon group structural formula:

Example 1

(1) Preparation of diamine monomer

a. Synthesis of intermediate 2-(4-fluorophenyl)-benzoxazole

7.65g (50mmol) of 2-chlorobenzoxazole, 7.0g (50mmol) of p-fluorophenylboronic acid, and 10.28g of potassium carbonate (75mmol) were added to a 250mL three-neck round bottom flask, and 100mL of tetrahydrofuran solution and 50mL of deionized water were added. , stir magnetically and pass argon, then add 0.05 g of tetrakistriphenylphosphine palladium, heat up to 90 °C, stir and react for 12 h, cool, pour the reaction solution into water for precipitation, extract with ethyl acetate, and separate the layers to obtain an organic layer , spin-dried, and purified by column chromatography to obtain 7.67 g of white product 2-(4-fluorophenyl)-benzoxazole with a yield of about 72%, and its structural formula is as follows:

b. Synthesis of Intermediate Substituted Dibromocarbazole Derivatives

6.39 g (30 mmol) of 2-(4-fluorophenyl)-benzoxazole, 9.75 g (30 mmol) of 3,6-dibromocarbazole, and 11.7 g (36 mmol) of cesium carbonate prepared in step a were added to 500 mL of three wells In a round-bottomed flask, add 300 mL of anhydrous DMF, stir magnetically and protect with argon gas, heat up to 150 °C for 12 h, cool down, pour the reaction solution into water to precipitate, filter and wash it with methanol, and mix it with ethyl acetate and ethyl acetate. It was recrystallized from petroleum ether and dried in a vacuum drying oven at 80° C. for 12 hours to obtain 12.4 g of a white intermediate product with a yield of about 80%. The intermediate structural formula is as follows:

c. Synthesis of para-substituted target diamine monomer Y-1

5.18g (10mmol) of substituted dibromocarbazole derivatives prepared in step b, 6.64g (24mmol) of potassium carbonate and 6.58g (24mmol) of 4-aminophenylboronic acid were added to a 250mL double-necked round bottom flask, and 80mL of tetrahydrofuran was added, 40mL of deionized water, stirred magnetically and protected by argon gas, then added 0.05g of tetrakistriphenylphosphine palladium, heated to 90 °C for 24 hours, cooled to room temperature, poured the reaction solution into water to precipitate, filtered and used methanol to fully After washing and drying, 4.45 g of the target diamine monomer was obtained by using column chromatography to purify, and the yield was about 82%, and its structural formula was as follows:

(2) Preparation of polyimide

At -10°C, 2.7110 g (5 mmol) of the diamine monomer prepared in step (1), 4.0048 g (20 mmol) of 4,4'-diaminodiphenyl ether and 30.5 mL of N-N dimethylformamide were added to Into a 150ml three-necked flask, argon protection was introduced. After stirring to dissolve completely, 5.6603 g (25.25 mmol) of hydrogenated pyromellitic anhydride was added, and the reaction was continued to stir at room temperature for 72 h to obtain a homogeneous, transparent and viscous polyamic acid solution.

(3) 47.26 ml of acetic anhydride and 18.91 ml of pyridine were dropwise added to the polyamic acid solution prepared in step (2), and the resulting The polyimide solution was slowly poured into 1 L of anhydrous ethanol, and precipitated, filtered, washed with distilled water, and dried in a vacuum oven at 150° C. to obtain polyimide powder.

(4) Dissolve the polyimide powder prepared in step (3) in 30 mL of N,N-dimethylformamide, and after it is completely dissolved, place the polyimide solution in a vacuum oven, vacuum After treatment for 0.5h, after the bubbles are eliminated, the polyimide solution is scraped on the clean glass substrate, and then the substrate is placed in a high-temperature vacuum oven, heated to 220 ° C to dry and remove the solvent, and polyimide can be obtained after cooling. membrane. The thermal weight loss curve of the polyimide film is shown in FIG. 1 , the fluorescence spectrum is shown in FIG. 2 , the infrared spectrum is shown in FIG. 3 , and the nuclear magnetic spectrum is shown in FIG. 4 . It can be seen from Figure 3 that the symmetric and asymmetric stretching vibration absorption peaks of the carbonyl group on the imide ring appear at 1721 cm ^-1 and 1776 cm ^-1 , and the 5% thermal decomposition temperature of the polyimide film is 488 °C, The strongest absorption peak of its fluorescence is 445nm.

(5) The molecular structural formula of the light-emitting polyimide in this embodiment is as follows:

Example 2

(1) Synthesis of meta-substituted target diamine monomer 2

The substituted dibromocarbazole derivatives 5.18g (10mmol), potassium carbonate 6.64g (24mmol) and 3-aminophenylboronic acid 6.58g (24mmol) prepared in step b in Example 1 were added to the 250mL double-necked round-bottomed flask, Add 80 mL of tetrahydrofuran, 40 mL of deionized water, stir magnetically and protect with argon, then add a catalytic amount of tetrakistriphenylphosphine palladium, heat up to 90 °C and react for 24 h, then cool to room temperature, pour the reaction solution into water for precipitation, After filtration, it was fully washed with methanol, dried and purified by column chromatography to obtain 4.07 g of the target diamine monomer with a yield of about 75%, and its structural formula is as follows:

(2) At -10°C, 2.1688 g (4 mmol) of the diamine monomer prepared in step (1), 3.2038 g (16 mmol) of 4,4'-diaminodiphenyl ether and 24.4 mL of N-N dimethyl methyl The amide was added to a 150ml three-necked flask and protected by argon. After stirring to dissolve completely, 4.5282 g (20.2 mmol) of hydrogenated pyromellitic anhydride was added, and the reaction was continued to stir for 72 h at room temperature to obtain a homogeneous, transparent and viscous polyamic acid solution.

(3) 37.81 ml of acetic anhydride and 15.13 ml of pyridine were dropwise added to the obtained polyamic acid solution, and the obtained polyimide solution was slowly stirred for 10 hours under the conditions of ambient humidity of 30%, 25° C. and argon gas. Poured into 1L of absolute ethanol, precipitated out, filtered, washed with distilled water, and dried in a vacuum oven at 150°C to obtain polyimide powder.

(4) Dissolve the above-mentioned polyimide powder in 24 mL of N,N-dimethylformamide, and after it is completely dissolved, place the polyimide solution in a vacuum oven, vacuumize for 0.5 h, and wait for After the bubbles are eliminated, the polyimide solution is scraped on the clean glass substrate, and then the substrate is placed in a high-temperature vacuum oven, heated to 150° C. to dry and remove the solvent, and the polyimide film can be obtained after cooling.

(5) The molecular structural formula of the light-emitting polyimide in this embodiment is as follows:

Example 3

(1) Preparation of diamine monomer

a. Synthesis of intermediate 2-(4-fluoro-2methylphenyl)-benzoxazole

7.65 g (50 mmol) of 2-chlorobenzoxazole, 7.7 g (50 mmol) of 4-fluoro-2-methylphenylboronic acid, and 10.28 g of potassium carbonate (75 mmol) were added to a 250 mL three-neck round bottom flask, and 100 mL of tetrahydrofuran was added. The solution, 50 mL of deionized water, magnetically stirred and argon was passed through, then 0.05 g of tetrakistriphenylphosphine palladium was added, the temperature was raised to 90 °C, stirred for 12 h, cooled, and the reaction solution was poured into water for precipitation, and extracted with ethyl acetate , the organic layer was obtained by liquid separation, spin-dried, and purified by column chromatography to obtain 8.52 g of a white product, 2-(4-fluoro-2methylphenyl)-benzoxazole, with a yield of about 75%, and its structural formula was as follows:

b. Synthesis of Intermediate Substituted Dibromocarbazole Derivatives

6.81 g (30 mmol) of 2-(4-fluoro-2methylphenyl)-benzoxazole, 9.75 g (30 mmol) of 3,6-dibromocarbazole, and 11.7 g (36 mmol) of cesium carbonate were added to 500 mL of three wells In a round-bottomed flask, add 300 mL of anhydrous DMF, stir magnetically and protect with argon gas, heat up to 150 °C for 12 h, cool down, pour the reaction solution into water to precipitate, filter and wash it with methanol, and mix it with ethyl acetate and ethyl acetate. It was recrystallized from petroleum ether and dried in a vacuum drying oven at 80° C. for 12 hours to obtain 11.81 g of a white intermediate product with a yield of about 74%. The intermediate structural formula is as follows:

c. Synthesis of para-substituted target diamine monomer 3

5.32g (10mmol) of substituted dibromocarbazole derivatives in the previous step, 6.64g (24mmol) of potassium carbonate and 6.58g (24mmol) of 4-aminophenylboronic acid were added to a 250mL double-necked round bottom flask, and 80mL of tetrahydrofuran was added, 40mL of deionized water, stirred magnetically and protected by argon gas, then added 0.05g of tetrakistriphenylphosphine palladium, heated to 90 °C for 24 hours, cooled to room temperature, poured the reaction solution into water to precipitate, filtered and used methanol to fully After washing and drying, 4.23 g of the target diamine monomer was obtained by using column chromatography to purify, and the yield was about 76%, and its structural formula was as follows:

(2) At -10°C, 1.6687 g (3 mmol) of the diamine monomer prepared in step (1), 2.4029 g (12 mmol) of 4,4'-diaminodiphenyl ether and 18 mL of N-N dimethylformamide were added It was added to a 150ml three-necked flask and protected by argon gas. After stirring to dissolve completely, 3.3962 g (15.15 mmol) of hydrogenated pyromellitic anhydride was added, and the reaction was continued to stir at room temperature for 72 h to obtain a homogeneous, transparent and viscous polyamic acid solution.

(3) 28.37 ml of acetic anhydride and 11.35 ml of pyridine were added dropwise to the obtained polyamic acid solution, and under the conditions of ambient humidity of 30%, 25° C., and argon, stirring was continued for 10 hours, and the obtained polyimide solution was added to the solution. Slowly poured into 1L of absolute ethanol, precipitated out, filtered, washed with distilled water, and dried in a 150°C vacuum oven to obtain polyimide powder.

(4) Dissolve the above-mentioned polyimide powder in 18 mL of N,N-dimethylformamide, and after it is completely dissolved, place the polyimide solution in a vacuum oven, and treat it for 0.5 h with bubbling. After the bubbles are eliminated, the polyimide solution is scraped on the clean glass substrate, and then the substrate is placed in a high-temperature vacuum oven, heated to 220° C. to dry and remove the solvent, and a polyimide film can be obtained after cooling.

(5) The molecular structural formula of the light-emitting polyimide in this embodiment is as follows:

Example 4

(1) Synthesis of meta-substituted target diamine monomer 4

In Example 3, 5.32g (10mmol) of substituted dibromo derivatives, 6.64g (24mmol) of potassium carbonate and 6.58g (24mmol) of 3-aminophenylboronic acid were added to a 250mL double-necked round bottom flask, 80mL of tetrahydrofuran was added, and 40mL of tetrahydrofuran was added. Ionized water was stirred magnetically and protected by argon, then a catalytic amount of tetrakistriphenylphosphine palladium was added, the temperature was raised to 90 °C and reacted for 24 h, cooled to room temperature, the reaction solution was poured into water for precipitation, filtered and washed with methanol. , after drying, 4.06 g of the target diamine monomer was obtained by purifying by column chromatography, and the yield was about 73%, and its structural formula was as follows:

(2) At -10°C, add 2.7812g (5mmol) of the above-mentioned diamine monomer, 4.0048g (20mmol) of 4,4'-diaminodiphenyl ether and 30mL of N-N dimethylformamide to a 150ml three-necked flask in the argon protection. After stirring to dissolve completely, 5.6603 g (25.25 mmol) of hydrogenated pyromellitic anhydride was added, and the reaction was continued to stir at room temperature for 72 h to obtain a homogeneous, transparent and viscous polyamic acid solution.

(3) 47.26 ml of acetic anhydride and 18.91 ml of pyridine were dropped into the obtained polyamic acid solution dropwise, and under the conditions of ambient humidity of 30%, 25° C., and argon, stirring was continued for 10 hours, and then the obtained polyimide solution was added. Slowly poured into 1L of absolute ethanol, precipitated out, filtered, washed with distilled water, and dried in a 150°C vacuum oven to obtain polyimide powder.

(4) Dissolve the above-mentioned polyimide powder in 30 mL of N,N-dimethylformamide, and after it is completely dissolved, place the polyimide solution in a vacuum oven, vacuumize for 0.5 h, and wait for After the bubbles are eliminated, the polyimide solution is scraped on the clean glass substrate, and then the substrate is placed in a high-temperature vacuum oven, heated to 220° C. to dry and remove the solvent, and a polyimide film can be obtained after cooling.

(5) The molecular structural formula of the light-emitting polyimide in this embodiment is as follows:

Example 5

Step (1) is with embodiment 1;

(2) At -10°C, 2.7110 g (5 mmol) of the diamine monomer synthesized in Example 1, 4.0048 g (20 mmol) of 4,4'-diaminodiphenyl ether and 30.5 mL of N-N dimethylformamide were added It was added to a 150ml three-necked flask and protected by argon gas. After stirring to dissolve completely, 5.6603 g (25.25 mmol) of hydrogenated pyromellitic anhydride was added, and the reaction was continued to stir at room temperature for 72 h to obtain a homogeneous, transparent and viscous polyamic acid solution.

(3) Place the polyamic acid solution in a vacuum oven, and perform bubbling treatment for 1 hour. After the bubbles are eliminated, scrape the polyamic acid solution on a clean glass substrate, and then place the substrate in a high-temperature vacuum oven. Heating up by program: from room temperature to 100°C, hold at 100°C±2°C for 1h, then heat up to 200°C, hold at 200°C±2°C for 1h, then heat up to 300°C, hold at 300°C±2°C Hold for 1h, then heat up to 370°C, and keep at 370°C±2°C for 0.5h. After the treatment, it was cooled to room temperature, and the substrate with the polyimide film was taken out and soaked in hot water at 100° C. to peel off the film. The obtained polyimide film was vacuum-dried at 180° C. to remove residual solvent to obtain a polyimide film.

Example 6

Step (1) is with embodiment 2;

(2) At -10°C, 2.1688 g (4 mmol) of the diamine monomer synthesized in Example 2, 3.2038 g (16 mmol) of 4,4'-diaminodiphenyl ether and 24.4 mL of N-N dimethylformamide were added It was added to a 150ml three-necked flask and protected by argon gas. After stirring to dissolve completely, 4.5282 g (20.2 mmol) of hydrogenated pyromellitic anhydride was added, and the reaction was continued to stir at room temperature for 72 h to obtain a homogeneous, transparent and viscous polyamic acid solution.

(3) Place the polyamic acid solution in a vacuum oven, and perform bubbling treatment for 1 hour. After the bubbles are eliminated, scrape the polyamic acid solution on a clean glass substrate, and then place the substrate in a high-temperature vacuum oven. Heating up by program: from room temperature to 100°C, hold at 100°C±2°C for 1h, then heat up to 200°C, hold at 200°C±2°C for 1h, then heat up to 300°C, hold at 300°C±2°C Hold for 1h, then heat up to 370°C, and keep at 370°C±2°C for 0.5h. After the treatment, it was cooled to room temperature, and the substrate with the polyimide film was taken out and soaked in hot water at 100° C. to peel off the film. The obtained polyimide film was vacuum-dried at 180° C. to remove residual solvent to obtain a polyimide film.

Example 7

Step (1) is with embodiment 3;

(2) 2.7812g (5mmol) of the diamine monomer synthesized in Example 3, 4.0048g (20mmol) of 4,4'-diaminodiphenyl ether and 30mL of N-N dimethylformamide were added at -10°C To a 150ml three-necked flask, pass through argon protection. After stirring to dissolve completely, 5.6603 g (25.25 mmol) of hydrogenated pyromellitic anhydride was added, and the reaction was continued to stir at room temperature for 72 h to obtain a homogeneous, transparent and viscous polyamic acid solution.

(3) Place the polyamic acid solution in a vacuum oven, and perform bubbling treatment for 1 hour. After the bubbles are eliminated, scrape the polyamic acid solution on a clean glass substrate, and then place the substrate in a high-temperature vacuum oven. Heating up by program: from room temperature to 100°C, hold at 100°C±2°C for 1h, then heat up to 200°C, hold at 200°C±2°C for 1h, then heat up to 300°C, hold at 300°C±2°C Hold for 1h, then heat up to 370°C, and keep at 370°C±2°C for 0.5h. After the treatment, it was cooled to room temperature, and the substrate with the polyimide film was taken out and soaked in hot water at 100° C. to peel off the film. The obtained polyimide film was vacuum-dried at 180° C. to remove residual solvent to obtain a polyimide film.

Example 8

Step (1) is with embodiment 4;

(2) 1.6687g (3mmol) of the diamine monomer synthesized in Example 4, 2.4029g (12mmol) of 4,4'-diaminodiphenyl ether and 184mL of N-N dimethylformamide were added at -10°C To a 150ml three-necked flask, pass through argon protection. After stirring to dissolve completely, 3.3962 g (15.15 mmol) of hydrogenated pyromellitic anhydride was added, and the reaction was continued to stir at room temperature for 72 h to obtain a homogeneous, transparent and viscous polyamic acid solution.

(3) Place the polyamic acid solution in a vacuum oven, and perform bubbling treatment for 1 hour. After the bubbles are eliminated, scrape the polyamic acid solution on a clean glass substrate, and then place the substrate in a high-temperature vacuum oven. Heating up by program: from room temperature to 100°C, hold at 100°C±2°C for 1h, then heat up to 200°C, hold at 200°C±2°C for 1h, then heat up to 300°C, hold at 300°C±2°C Hold for 1h, then heat up to 370°C, and keep at 370°C±2°C for 0.5h. After the treatment, it was cooled to room temperature, and the substrate with the polyimide film was taken out and soaked in hot water at 100° C. to peel off the film. The obtained polyimide film was vacuum-dried at 180° C. to remove residual solvent to obtain a polyimide film.

Claims (7)

1. A polyimide containing benzoxazole and carbazole structures is characterized in that the structural formula of the polyimide is as follows:

wherein n and m represent polymerization degrees, n/m is 1/99-100/0, X and W are tetravalent aromatic groups or aliphatic groups, Z is a divalent aromatic group or aliphatic group, and Y is one or two mixtures of groups represented by the general structural formula Y-1 or Y-2:

r in the general structural formula Y-1 or Y-2₁、R₂、R₃、R₄Selected from any one of the following structural formulas:

the X or W is the same or different and is selected from one or more than one of the following quadrivalent aromatic group or aliphatic group structural formulas:

z is selected from any one of the following bivalent aromatic group or aliphatic group structural formulas:

2. the method for preparing polyimide containing benzoxazole and carbazole structures according to claim 1, comprising the steps of: in an argon or nitrogen atmosphere, a diamine monomer containing a Y structure or a mixed diamine containing an Y, Z structure and a dianhydride containing an X structure or a mixed dianhydride containing a X, W structure are mixed according to a molar ratio of 1: (1-1.1) dissolving in an aprotic polar organic solvent, stirring and reacting at-10-40 ℃ for 6-72 hours to obtain a polyamic acid solution, and then performing imidization by a thermal imidization method or a chemical imidization method to obtain the polyimide.

3. The preparation method of the polyimide containing the benzoxazole and carbazole structures according to claim 2, wherein the total mass of the diamine monomer containing the Y structure or the mixed diamine monomer containing the Y and Z structures and the dianhydride monomer containing the X structure or the mixed dianhydride monomer containing the X and W structures accounts for 5-50% of the total mass of the reaction materials.

4. The method of claim 2, wherein the aprotic polar organic solvent is one or a mixture of two or more selected from the group consisting of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, dimethylsulfone, 1, 4-dioxane, tetrahydrofuran, and m-cresol.

5. The method for preparing polyimide containing benzoxazole and carbazole structures according to claim 2, wherein said thermal imidization method is used to prepare polyimide, and comprises the following steps: placing a polyamic acid solution in a vacuum oven, carrying out bubble pumping treatment, coating the polyamic acid solution on a clean substrate in a blade mode, then placing the substrate in a high-temperature vacuum oven, and heating according to a set program: heating from room temperature to 100 ℃, keeping at 100 ℃ +/-2 ℃ for 1h, then heating to 200 ℃, keeping at 200 ℃ +/-2 ℃ for 1h, then heating to 300 ℃, keeping at 300 ℃ +/-2 ℃ for 1h, then heating to 370 ℃, and keeping at 370 ℃ +/-2 ℃ for 0.5 h; and cooling to room temperature after the treatment is finished, taking out the substrate with the polyimide film, soaking in hot water at the temperature of 80-100 ℃ to strip the film, and drying in vacuum at the temperature of 180 ℃ to obtain the polyimide film.

6. The method for preparing polyimide containing benzoxazole and carbazole structures according to claim 2, wherein said chemical imidization method comprises the following steps:

(1) adding acetic anhydride and pyridine into a polyamic acid solution to ensure that the molar ratio of-COOH in the acetic anhydride and the polyamic acid solution is 10:1 and the molar ratio of the acetic anhydride to the pyridine is 5:2, stirring for 8-15h under the conditions that the ambient humidity is lower than 40%, the ambient temperature is 0-30 ℃ and argon is used, dropwise adding the obtained solution into an absolute ethyl alcohol or methanol solution to precipitate out, filtering, washing with distilled water, and fully drying in a vacuum oven at 150 ℃ to obtain a polyimide powder material;

(2) dissolving the polyimide powder material in an aprotic polar organic solvent, placing the solution in a vacuum oven at room temperature, vacuumizing to remove bubbles, scraping the polyimide solution on a clean substrate after bubbles are removed, placing the substrate in a high-temperature vacuum oven, heating to 70-300 ℃, drying, and cooling to obtain the polyimide film.

7. Use of the polyimide containing benzoxazole and carbazole structures according to claim 1 in the preparation of light-emitting layer materials, photoluminescent materials, and flexible electroluminescent devices in optical devices.

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