Pyridine-containing terphenyl diamine, colorless transparent polyimide and preparation method and application thereof

Abstract

The invention belongs to the field of optical films, and particularly relates to pyridine-containing terphenyl diamine, colorless transparent polyimide as well as a preparation method and application thereof. The structural formula of the pyridine-containing terphenyl diamine is shown as a formula (1). According to the invention, substituent groups on diamine monomers are adjusted, methyl groups at para-positions of nitrogen atoms on pyridine are changed, six different pyridine-containing terphenyl diamines are designed and introduced into polyimide, and the charge transfer effect, molecular spacing and folding degree of a polyimide chain are adjusted; the colorless transparent polyimide film with heat resistance, good optical performance and tensile strength is obtained. The method has potential application value in the field of flexible devices. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of optical materials, and specifically relates to a pyridine-containing terphenyl diamine, a colorless transparent polyimide, and a preparation method and application thereof. Background Art

[0002] With the development of science and technology, new flexible display technology has received more and more attention. It has many advantages such as low power consumption, thin and light, convenient and beautiful, and base film materials are indispensable optical components. Traditional flexible substrate materials are prone to yellowing under high temperature or chemical environment, which affects the display effect, and the mechanical properties are insufficient. It is difficult to withstand repeated bending and stretching, and cannot meet the high requirements of modern flexible display technology. Due to the imide bond in the main chain, polyimide has excellent comprehensive properties, such as heat resistance and mechanical properties. Traditional polyimide is usually golden yellow, which is characterized by a highly conjugated molecular chain structure and strong intermolecular / intramolecular charge interaction, which limits their application in optical engineering. Therefore, the optical properties of polyimide can be improved by adjusting the charge transfer complexation effect between polyimide molecules, so as to meet the requirements of flexible display base film.

[0003] At present, new flexible display technologies require the base film to have good optical properties and heat resistance, as well as excellent mechanical properties to withstand repeated bending and stretching, which is a huge challenge for colorless and transparent polyimide.

[0004] Chinese patent application CN117843499A discloses a class of asymmetric diamines, high-performance polyimides, and preparation methods and applications thereof. The present invention adjusts the substituent at the second position on the diamine monomer, designs four different asymmetric diamines and introduces them into the polyimide, adjusts the charge transfer effect and molecular distance of the polyimide chain, and obtains a colorless and transparent polyimide film with both heat resistance and high transmittance. However, the mechanical properties of the colorless and transparent polyimide film are still not ideal. Summary of the invention

[0005] In order to solve the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a terphenyl diamine containing pyridine.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned pyridine-containing terphenyl diamine.

[0007] Another object of the present invention is to provide a colorless and transparent polyimide of terphenyl diamine containing pyridine. The present invention introduces an electron-deficient pyridine structure on the main chain, designs a terphenyl with a unique curved structure, adjusts the substituents, designs six new diamines with different structures, adjusts the charge transfer effect and molecular chain spacing of the polyimide chain, and constructs a spiral folding structure to obtain a colorless and transparent polyimide film with heat resistance, good transmittance and mechanical properties.

[0008] The present invention also provides application of the colorless and transparent polyimide of the terphenyl diamine containing pyridine in the field of flexible electronics.

[0009] The technical solution of the present invention is as follows:

[0010] The pyridine-containing terphenyl diamine proposed in the present invention has a structural formula as shown in formula (1):

[0011]

[0012] In the formula, R1 is trifluoromethyl, methyl or fluoro; R2 is hydrogen or methyl.

[0013] In the present invention, the diamine in which R1 is a fluorine group and R2 is a hydrogen group is referred to as 2F-PTPDA, and the structural formula is:

[0014]

[0015] Among them, the diamine in which R1 is trifluoromethyl and R2 is hydrogen is referred to as 6F-PTPDA, and the structural formula is:

[0016]

[0017] Among them, the diamine in which R1 is methyl and R2 is hydrogen is referred to as 6H-PTPDA, and the structural formula is:

[0018]

[0019] Among them, the diamine in which R1 is a fluorine group and R2 is a methyl group is referred to as 2F-MPTPDA, and the structural formula is:

[0020]

[0021] Among them, the diamine in which R1 is trifluoromethyl and R2 is methyl is referred to as 6F-MPTPDA, and the structural formula is:

[0022]

[0023] Among them, the diamine with R1 being methyl and R2 being methyl is referred to as 6H-MPTPDA, and the structural formula is:

[0024]

[0025] The method for preparing terphenyl diamine containing pyridine of the present invention comprises the following steps:

[0026] S1. Place a bromine-substituted 4-nitrobenzene compound, bipyraclostrobin, potassium acetate, 1,1'-bis(diphenylphosphino)ferrocenepalladium dichloride, and 1,4-dioxane in a reaction vessel, stir and heat to 80-90° C. under inert gas conditions, and condense and reflux for 21-24 hours to obtain a monomer M;

[0027] S2. Monomer M, a dibromo-substituted pyridine compound, potassium carbonate, water, tetrakis(triphenylphosphine)palladium, ethanol and toluene are placed in a reaction vessel, and under inert gas conditions, the temperature is raised to 100 to 120° C. with stirring and refluxed for 20.5 to 24 hours to obtain a pyridine-containing terphenyl dinitro monomer NM;

[0028] S3. Under room temperature, add pyridine-containing terphenyl dinitro monomer NM, anhydrous ethanol and Pd / C into a reaction vessel. Under inert gas conditions, stir and heat to 80°C for condensation reflux. Add hydrazine hydrate dropwise to the mixed solution in the reaction vessel. After the addition is complete, maintain the temperature at 80°C for 10 to 12 hours to obtain the pyridine-containing terphenyl diamine.

[0029] The bromine-substituted 4-nitrobenzene compound in step S1 is 1-bromo-2-fluoro-4-nitrobenzene, 2-bromo-5-nitrotoluene or 2-bromo-5-nitrotrifluorotoluene; the dibromo-substituted pyridine compound in step S2 is 3,5-dibromopyridine or 3,5-dibromo-4-methylpyridine.

[0030] In step S1: when the bromine-substituted 4-nitrobenzene compound is 1-bromo-2-fluoro-4-nitrobenzene, the obtained monomer M is 2-(2-fluoro-4-nitrophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane, having the structural formula

[0031] When the bromine-substituted 4-nitrobenzene compound is 2-bromo-5-nitrotrifluorotoluene, the monomer M prepared in step S1 is 2-(2-trifluoromethyl-4-nitrophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane, having the structural formula

[0032] When the bromine-substituted 4-nitrobenzene compound is 2-bromo-5-nitrotoluene, the monomer M prepared in step S1 is 2-(2-methyl-4-nitrophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane, having the structural formula

[0033] In step S1, the molar ratio of the bromine-substituted 4-nitrobenzene compound, pinacol diboron, potassium acetate, and 1,1'-bis(diphenylphosphino)ferrocenepalladium dichloride is 10 mmol: 12 mmol: 32.24 mmol: 0.21 mmol. 1,4-Dioxane is used as a solvent, and the volume does not need to be strictly limited.

[0034] In step S1, after the condensation reflux is completed, the method further includes: cooling the reaction solution; diluting the mixture with ethyl acetate and washing it three times with deionized water; drying the organic layer with anhydrous magnesium sulfate, then removing the anhydrous magnesium sulfate by filtration, concentrating the filtrate in vacuo to obtain a crude product, and finally purifying the crude product by silica gel column chromatography.

[0035] The eluent of the silica gel column chromatography is dichloromethane: petroleum ether in a volume ratio of 1:8-10.

[0036] In step S2: when the monomer M is 2-(2-fluoro-4-nitrophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane and the dibromo-substituted pyridine compound is 3,5-dibromopyridine, the obtained pyridine-containing terphenyl dinitro monomer NM-1 has the structural formula

[0037] When the monomer M is 2-(2-trifluoromethyl-4-nitrophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane and the dibromo-substituted pyridine compound is 3,5-dibromopyridine, the obtained pyridine-containing terphenyl dinitro monomer NM-2 has the structural formula

[0038] When the monomer M is 2-(2-methyl-4-nitrophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane and the dibromo-substituted pyridine compound is 3,5-dibromopyridine, the obtained pyridine-containing terphenyl dinitro monomer NM-3 has the structural formula

[0039] When the monomer M is 2-(2-fluoro-4-nitrophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane and the dibromo-substituted pyridine compound is 3,5-dibromo-4-methylpyridine, the obtained pyridine-containing terphenyl dinitro monomer NM-4 has the structural formula

[0040] When the monomer M is 2-(2-trifluoromethyl-4-nitrophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane and the dibromo-substituted pyridine compound is 3,5-dibromo-4-methylpyridine, the obtained pyridine-containing terphenyl dinitro monomer NM-5 has the structural formula

[0041] When the monomer M is 2-(2-methyl-4-nitrophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane and the dibromo-substituted pyridine compound is 3,5-dibromo-4-methylpyridine, the obtained pyridine-containing terphenyl dinitro monomer NM-6 has the structural formula

[0042] In step S2, the molar ratio of the monomer M, the dibromo-substituted pyridine compound, potassium carbonate and tetrakis(triphenylphosphine)palladium is 3:1:13.5:0.15. The toluene, ethanol and water are used as solvents, and the amount does not need to be strictly limited. The molar volume ratio of the dibromo-substituted pyridine compound to toluene, ethanol and water is preferably 2mmol:8mL:4mL:8mL.

[0043] In step S2, after the condensation reflux is completed, the method further includes: diluting the mixture with dichloromethane and washing it three times with deionized water; drying the organic layer with anhydrous magnesium sulfate, then removing the anhydrous magnesium sulfate by filtration, concentrating the filtrate in vacuo to obtain a crude product, and finally purifying the crude product by silica gel column chromatography.

[0044] The eluent of the silica gel column chromatography is dichloromethane: petroleum ether in a volume ratio of 4:1.

[0045] In step S3, the ratio of the pyridine-containing terphenyl dinitro monomer NM, Pd / C and anhydrous ethanol is 3 g:0.68 g:60 mL; the ratio of the pyridine-containing terphenyl dinitro monomer NM and hydrazine hydrate is 3 g:6.32 mL.

[0046] In step S3, the dripping speed of the hydrazine hydrate is one drop every two seconds.

[0047] In step S3, after the isothermal reaction is completed, the following steps are further included: filtering while hot to remove Pd / C, pouring the filtrate into cold water, stirring and adding sodium chloride until solids are precipitated, filtering the solids and washing them with an ethanol / water mixed solution, and vacuum drying the filtered solids to obtain a pyridine-containing terphenyl diamine monomer.

[0048] In step S1, condensation reflux is preferably performed at 80° C. for 24 h;

[0049] In step S2, preferably, the mixture is stirred and heated to 110° C. for condensation and reflux for 24 hours;

[0050] In step S3, after the dropwise addition of hydrazine hydrate is completed, the reaction is preferably maintained at 80° C. for 12 hours.

[0051] The present invention also provides a polyimide polymer prepared by polycondensation of the above-mentioned pyridine-containing terphenyl diamine monomer, which comprises the following repeating units:

[0052]

[0053] Among them, R1 is fluoro, trifluoromethyl or methyl, R2 is hydrogen or methyl, and n is preferably 43-77.

[0054] In the formula (2) of the present invention, R2 is hydrogen, R1 is a fluoro group, a trifluoromethyl group or a methyl group, and the polyimide polymers are respectively abbreviated as 6FDA-2F-PTPDA, 6FDA-6F-PTPDA, and 6FDA-6H-PTPDA; R2 is methyl, R1 is a fluoro group, a trifluoromethyl group or a methyl group, and the polyimide polymers are respectively abbreviated as 6FDA-2F-MPTPDA, 6FDA-6F-MPTPDA, and 6FDA-6H-MPTPDA.

[0055] The pyridine-containing terphenyl diamine monomer of the present invention can be further polycondensed to prepare a polyimide polymer, comprising the following steps: placing the pyridine-containing terphenyl diamine monomer of formula (1), a tetracarboxylic dianhydride monomer and m-cresol in a reaction container, heating the reaction mixture to 60-80° C. (preferably 80° C.), stirring the reaction mixture at a constant temperature for 0.5-1 h (preferably 1 h), adding a catalyst, and then heating the reaction mixture to 180-185° C. and stirring the reaction mixture at a constant temperature for 8-10 h (preferably 180° C. and stirring the reaction mixture at a constant temperature for 10 h), thereby preparing a polyimide polymer through a one-step polycondensation reaction;

[0056] The tetracarboxylic dianhydride monomer structural formula is as follows (abbreviated as 6FDA):

[0057]

[0058] Preferably, the molar ratio of the tetracarboxylic dianhydride monomer to the pyridine-containing terphenyl diamine monomer is 1:1.

[0059] Preferably, the catalyst is isoquinoline.

[0060] Preferably, the method further comprises dissolving the polyimide in N,N-dimethylacetamide, degassing by centrifugation, then coating the polyimide by blade coating, and forming the polyimide by high temperature in a vacuum oven.

[0061] More preferably, after the polyimide is dissolved in N,N-dimethylacetamide, the solid content of the polyimide is 15%, and the centrifugal parameter is 5000 r min -1 , 5min, and the heating time in the vacuum oven is successively at 80℃ for 1h, 150℃ for 2h, 200℃ for 2h and 220℃ for 2h.

[0062] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0063] 1. A series of new colorless and transparent polyimides of terphenyl diamine containing pyridine were successfully prepared, and the effect of adjusting the diamine structure on the performance of polyimide films was systematically explored.

[0064] 2. Different diamine groups have different electron-withdrawing effects, which can help regulate charge transfer. At the same time, the methyl group on the nitrogen atom of pyridine can further adjust the folding effect of the polyimide molecular chain, further adjust the mechanical properties of the polyimide material, and coordinate the thermal and optical properties.

[0065] 3. The prepared colorless and transparent polyimide has good optical transparency (82.6% to 89.3%) and bending resistance (20,000 bending times). It also exhibits good heat resistance (290.2°C to 342.6°C) and a high tensile strength (85MPa to 108MPa), and has potential application value in the field of flexible displays. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 These are the hydrogen spectrum and carbon spectrum of the pyridine-containing terphenyl dinitro monomer NM-1 prepared in Example 1.

[0067] Figure 2 These are the hydrogen spectrum and carbon spectrum of the pyridine-containing terphenyl diamine monomer 2F-PTPDA prepared in Example 1.

[0068] Figure 3 These are the hydrogen spectrum and carbon spectrum of the pyridine-containing terphenyl dinitro monomer NM-2 prepared in Example 2.

[0069] Figure 4 These are the hydrogen spectrum and carbon spectrum of the pyridine-containing terphenyl diamine monomer 6F-PTPDA prepared in Example 2.

[0070] Figure 5 These are the hydrogen spectrum and carbon spectrum of the pyridine-containing terphenyl dinitro monomer NM-3 prepared in Example 3.

[0071] Figure 6 These are the hydrogen spectrum and carbon spectrum of the pyridine-containing terphenyl diamine monomer 6H-PTPDA prepared in Example 3.

[0072] Figure 7 These are the hydrogen spectrum and carbon spectrum of the pyridine-containing terphenyl dinitro monomer NM-4 prepared in Example 4.

[0073] Figure 8 These are the hydrogen spectrum and carbon spectrum of the pyridine-containing terphenyl diamine monomer 2F-MPTPDA prepared in Example 4.

[0074] Fig. 9 These are the hydrogen spectrum and carbon spectrum of the pyridine-containing terphenyl dinitro monomer NM-5 prepared in Example 5.

[0075] Fig.10 These are the hydrogen spectrum and carbon spectrum of the pyridine-containing terphenyl diamine monomer 6F-MPTPDA prepared in Example 5.

[0076] Fig.11 These are the hydrogen spectrum and carbon spectrum of the pyridine-containing terphenyl dinitro monomer NM-6 prepared in Example 6.

[0077] Fig.12 These are the hydrogen spectrum and carbon spectrum of the pyridine-containing terphenyl diamine monomer 6H-MPTPDA prepared in Example 6.

[0078] Fig.13 These are hydrogen spectra of polyimide 6FDA-2F-PTPDA, 6FDA-6F-PTPDA, 6FDA-6H-PTPDA, 6FDA-2F-MPTPDA, 6FDA-6F-MPTPDA and 6FDA-6H-MPTPDA prepared in Examples 1, 2, 3, 4, 5 and 6. DETAILED DESCRIPTION

[0079] The present invention is further described in detail below in conjunction with the examples and drawings, but the embodiments of the present invention are not limited thereto. The raw materials involved in the present invention can be purchased directly from the market. For process parameters not particularly noted, conventional techniques can be used.

[0080] Example 1

[0081] Synthesis of pyridine-containing terphenyl diamine 2F-PTPDA monomer:

[0082] Synthesis of 2-(2-fluoro-4-nitrophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane monomer M1: 1-bromo-2-fluoro-4-nitrobenzene (10mmol), biboric acid pinacol ester (12mmol), potassium acetate (32.24mmol), 1,1'-bis(diphenylphosphino)ferrocene palladium dichloride (0.21mmol), and 60mL of 1,4-dioxane were placed in a three-necked flask, stirred under nitrogen and heated to 80°C for condensation reflux for 24h, and cooled after the constant temperature reaction; the mixture was diluted with 50mL of ethyl acetate and washed three times with 50mL of deionized water. The organic layer was dried with anhydrous magnesium sulfate, and then the anhydrous magnesium sulfate was removed by filtration, and the filtrate was vacuum concentrated to obtain a crude product, and finally the crude product was purified by silica gel column chromatography to obtain a light yellow powder with a yield of 69%.

[0083] Synthesis of pyridine-containing terphenyl dinitro monomer NM-1: Under nitrogen conditions, 6mmol of M1, 2mmol of 3,5-dibromopyridine, 27mmol of potassium carbonate, 8mL of deionized water, 0.3mmol of tetrakis(triphenylphosphine)palladium, 4mL of ethanol and 8mL of toluene were placed in a three-necked flask and frozen and pumped 3 times to remove oxygen. Stir and heat to 110℃ for condensation reflux for 24h, and cool after the constant temperature reaction; dilute the mixture with 100mL of dichloromethane and wash three times with 100mL of deionized water. The organic layer was dried with anhydrous magnesium sulfate, and then the anhydrous magnesium sulfate was removed by filtration. The filtrate was vacuum concentrated to obtain a crude product, and finally the crude product was purified by silica gel column chromatography with a yield of 76.8%.

[0084] Synthesis of pyridine-containing terphenyl diamine monomer 2F-PTPDA: 3 g of NM-1, 60 mL of anhydrous ethanol and 0.68 g of Pd / C were added to a three-necked flask, and the temperature was stirred and heated to 80°C under nitrogen for condensation and reflux. The temperature was maintained, and 6.32 mL of hydrazine hydrate was added dropwise to the mixed solution in the three-necked flask using a constant pressure funnel (the dropping speed was one drop every two seconds). After the addition was completed, the temperature was maintained for 12 hours. After the constant temperature reaction was completed, the heating was stopped, and the Pd / C was removed by hot filtration. The filtrate was poured into cold water, and sodium chloride was added while stirring until a solid was precipitated. The solid was filtered out and washed with an ethanol\water mixed solution, and then the filtered solid was vacuum dried to obtain the pyridine-containing terphenyl diamine monomer 2F-PTPDA;

[0085] Synthesis of polyimide 6FDA-2F-PTPDA: Under a nitrogen atmosphere, 10 mmol of 2F-PTPDA and 10 mmol of 6FDA were put into a three-necked flask, 32 mL of m-cresol and 8 mL of toluene were added, the temperature was raised to 80°C, and 4 mL of isoquinoline was added after constant stirring for 1 h. The temperature was then raised to 180°C and constant stirring was performed for 10 h. After the constant temperature reaction was completed, the mixture was cooled to room temperature, poured into 100 mL of methanol to precipitate a solid, filtered out the solid and washed with hot methanol, and the filtered solid was vacuum dried to obtain 6FDA-2F-PTPDA.

[0086] High temperature film formation by blade coating: 1.2 g of 6FDA-2F-PTPDA was dissolved in 6.8 g of DMAc, and then centrifuged for degassing (5000 r min -1 The film was formed by scraping and then coating in a vacuum oven at high temperature. The heating time was successively at 80° C. for 1 h, 150° C. for 2 h, 200° C. for 2 h and 220° C. for 2 h.

[0087] Example 2

[0088] Synthesis of pyridine-containing terphenyl diamine 6F-PTPDA monomer:

[0089] Synthesis of 2-(2-trifluoromethyl-4-nitrophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane monomer M2: 2-bromo-5-nitrotrifluorotoluene (10mmol), biboronic acid pinacol ester (12mmol), potassium acetate (32.24mmol), 1,1'-bis(diphenylphosphino)ferrocene palladium dichloride (0.21mmol), and 60mL1,4-dioxane were placed in a three-necked flask, stirred under nitrogen and heated to 80°C for condensation reflux for 24h, and cooled after the constant temperature reaction; the mixture was diluted with ethyl acetate and washed three times with deionized water. The organic layer was dried with anhydrous magnesium sulfate, and then the anhydrous magnesium sulfate was removed by filtration, and the filtrate was vacuum concentrated to obtain a crude product, and finally the crude product was purified by silica gel column chromatography to obtain a white powder with a yield of 73%.

[0090] Synthesis of pyridine-containing terphenyl dinitro monomer NM-2: Under nitrogen conditions, 6mmol of M2, 2mmol of 3,5-dibromopyridine, 27mmol of potassium carbonate, 8mL of deionized water, 0.3mmol of tetrakis(triphenylphosphine)palladium, 4mL of ethanol and 8mL of toluene were placed in a three-necked flask and frozen and pumped 3 times to remove oxygen. Stir and heat to 110℃ for condensation reflux for 24h, and cool after the constant temperature reaction; dilute the mixture with 100mL of dichloromethane and wash three times with 100mL of deionized water. The organic layer was dried with anhydrous magnesium sulfate, and then the anhydrous magnesium sulfate was removed by filtration. The filtrate was vacuum concentrated to obtain a crude product, and finally the crude product was purified by silica gel column chromatography with a yield of 77.2%.

[0091] Synthesis of pyridine-containing terphenyl diamine monomer 6F-PTPDA: 3 g of NM-2, 60 mL of anhydrous ethanol and 0.68 g of Pd / C were added to a three-necked flask, stirred and heated to 80°C under nitrogen conditions for condensation and reflux, and the temperature was maintained. 6.32 mL of hydrazine hydrate was added dropwise to the mixed solution in the three-necked flask using a constant pressure funnel (the dropping speed was one drop every two seconds). After the addition was completed, the temperature was maintained for 12 hours. After the constant temperature reaction was completed, heating was stopped, and Pd / C was removed by hot filtration. The filtrate was poured into cold water, and sodium chloride was added while stirring until a solid precipitated. The solid was filtered out and washed with an ethanol\water mixed solution, and then the filtered solid was vacuum dried to obtain the pyridine-containing terphenyl diamine monomer 6F-PTPDA;

[0092] Synthesis of polyimide 6FDA-6F-PTPDA: Under a nitrogen atmosphere, 10 mmol of 6F-PTPDA and 10 mmol of 6FDA were put into a three-necked flask, 32 mL of m-cresol and 8 mL of toluene were added, the temperature was raised to 80°C, and 4 mL of isoquinoline was added after constant stirring for 1 h. The temperature was then raised to 180°C and constant stirring was performed for 10 h. After the constant temperature reaction was completed, the mixture was cooled to room temperature, poured into 100 mL of methanol to precipitate a solid, filtered out the solid and washed with hot methanol, and the filtered solid was vacuum dried to obtain 6FDA-6F-PTPDA.

[0093] High temperature film formation by blade coating: 1.2 g of 6FDA-2F-PTPDA was dissolved in 6.8 g of DMAc, and then centrifuged for degassing (5000 r min -1 The film was formed by scraping and then coating in a vacuum oven at high temperature. The heating time was successively at 80° C. for 1 h, 150° C. for 2 h, 200° C. for 2 h and 220° C. for 2 h.

[0094] Example 3

[0095] Synthesis of pyridine-containing terphenyl diamine 6H-PTPDA monomer:

[0096] Synthesis of 2-(2-methyl-4-nitrophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane monomer M3: 2-bromo-5-nitrotoluene (10mmol), biboronic acid pinacol ester (12mmol), potassium acetate (32.24mmol), 1,1'-bis(diphenylphosphino)ferrocene palladium dichloride (0.21mmol), and 60mL1,4-dioxane were placed in a three-necked flask, stirred under nitrogen and heated to 80°C for condensation reflux for 24h, and cooled after the constant temperature reaction; the mixture was diluted with ethyl acetate and washed three times with deionized water. The organic layer was dried with anhydrous magnesium sulfate, and then the anhydrous magnesium sulfate was removed by filtration, and the filtrate was vacuum concentrated to obtain a crude product, and finally the crude product was purified by silica gel column chromatography to obtain a light yellow powder with a yield of 69%.

[0097] Synthesis of pyridine-containing terphenyl dinitro monomer NM-3: Under nitrogen conditions, 6mmol of M3, 2mmol of 3,5-dibromopyridine, 27mmol of potassium carbonate, 8mL of deionized water, 0.3mmol of tetrakis(triphenylphosphine)palladium, 4mL of ethanol and 8mL of toluene were placed in a three-necked flask and frozen and pumped 3 times to remove oxygen. Stir and heat to 110℃ for condensation reflux for 24h, and cool after the constant temperature reaction; dilute the mixture with 100mL of dichloromethane and wash three times with 100mL of deionized water. The organic layer was dried with anhydrous magnesium sulfate, and then the anhydrous magnesium sulfate was removed by filtration. The filtrate was vacuum concentrated to obtain a crude product, and finally the crude product was purified by silica gel column chromatography with a yield of 79.6%.

[0098] Synthesis of pyridine-containing terphenyl diamine monomer 6H-PTPDA: 3 g of NM-3, 60 mL of anhydrous ethanol and 0.68 g of Pd / C were added to a three-necked flask, and the temperature was stirred and heated to 80°C under nitrogen for condensation and reflux. The temperature was maintained, and 6.32 mL of hydrazine hydrate was added dropwise to the mixed solution in the three-necked flask using a constant pressure funnel (the dropping speed was one drop every two seconds). After the addition was completed, the temperature was maintained for 12 hours. After the constant temperature reaction was completed, the heating was stopped, and the Pd / C was removed by hot filtration. The filtrate was poured into cold water, and sodium chloride was added while stirring until a solid was precipitated. The solid was filtered out and washed with an ethanol\water mixed solution, and then the filtered solid was vacuum dried to obtain the pyridine-containing terphenyl diamine monomer 6H-PTPDA;

[0099] Synthesis of polyimide 6FDA-6H-PTPDA: Under a nitrogen atmosphere, 10 mmol of 6H-PTPDA and 10 mmol of 6FDA were put into a three-necked flask, 32 mL of m-cresol and 8 mL of toluene were added, the temperature was raised to 80°C, and 4 mL of isoquinoline was added after constant stirring for 1 h. The temperature was then raised to 180°C and constant stirring was performed for 10 h. After the constant temperature reaction was completed, the mixture was cooled to room temperature, poured into 100 mL of methanol to precipitate a solid, filtered out the solid and washed with hot methanol, and the filtered solid was vacuum dried to obtain 6FDA-6H-PTPDA.

[0100] High temperature film formation by blade coating: 1.2 g of 6FDA-6H-PTPDA was dissolved in 6.8 g of DMAc, and then centrifuged for degassing (5000 r min -1 The film was formed by scraping and then coating in a vacuum oven at high temperature. The heating time was successively at 80° C. for 1 h, 150° C. for 2 h, 200° C. for 2 h and 220° C. for 2 h.

[0101] Example 4

[0102] Synthesis of pyridine-containing terphenyl diamine 2F-MPTPDA monomer:

[0103] Synthesis of pyridine-containing terphenyl dinitro monomer NM-4: 6mmol of M1, 2mmol of 3,5-dibromo-4-methylpyridine, 27mmol of potassium carbonate, 8mL of deionized water, 0.3mmol of tetrakis(triphenylphosphine)palladium, 4mL of ethanol and 8mL of toluene were placed in a three-necked flask and frozen and pumped 3 times to remove oxygen. Stir and heat to 110°C for condensation reflux for 24h, and cool after the constant temperature reaction; dilute the mixture with 100mL of dichloromethane and wash three times with 100mL of deionized water. The organic layer was dried with anhydrous magnesium sulfate, and then the anhydrous magnesium sulfate was removed by filtration. The filtrate was vacuum concentrated to obtain a crude product, and finally the crude product was purified by silica gel column chromatography with a yield of 53.0%.

[0104] Synthesis of pyridine-containing terphenyl diamine monomer 2F-MPTPDA: 3 g of NM-4, 60 mL of anhydrous ethanol and 0.68 g of Pd / C were added to a three-necked flask, and the temperature was stirred and heated to 80° C. under nitrogen conditions for condensation and reflux. The temperature was maintained, and 6.32 mL of hydrazine hydrate was added dropwise to the mixed solution in the three-necked flask using a constant pressure funnel (the dropping speed was one drop every two seconds). After the addition was completed, the temperature was maintained for 12 hours. After the constant temperature reaction was completed, the heating was stopped, and the Pd / C was removed by hot filtration. The filtrate was poured into cold water, and sodium chloride was added while stirring until a solid was precipitated. The solid was filtered out and washed with an ethanol\water mixed solution, and then the filtered solid was vacuum dried to obtain the pyridine-containing terphenyl diamine monomer 2F-MPTPDA;

[0105] Synthesis of polyimide 6FDA-2F-MPTPDA: Under a nitrogen atmosphere, 10 mmol of 2F-MPTPDA and 10 mmol of 6FDA were put into a three-necked flask, 32 mL of m-cresol and 8 mL of toluene were added, the temperature was raised to 80°C, and 4 mL of isoquinoline was added after constant stirring for 1 h. The temperature was then raised to 180°C and constant stirring was performed for 10 h. After the constant temperature reaction was completed, the mixture was cooled to room temperature, poured into 100 mL of methanol to precipitate a solid, filtered out the solid and washed with hot methanol, and the filtered solid was vacuum dried to obtain 6FDA-2F-MPTPDA.

[0106] High temperature film formation by blade coating: 1.2 g of 6FDA-2F-MPTPDA was dissolved in 6.8 g of DMAc, and then centrifuged for degassing (5000 r min -1 The film was formed by scraping and then coating in a vacuum oven at high temperature. The heating time was successively at 80° C. for 1 h, 150° C. for 2 h, 200° C. for 2 h and 220° C. for 2 h.

[0107] Example 5

[0108] Synthesis of pyridine-containing terphenyl diamine 6F-MPTPDA monomer:

[0109] Synthesis of pyridine-containing terphenyl dinitro monomer NM-5: 6mmol of M2, 2mmol of 3,5-dibromo-4-methylpyridine, 27mmol of potassium carbonate, 8mL of deionized water, 0.3mmol of tetrakis(triphenylphosphine)palladium, 4mL of ethanol and 8mL of toluene were placed in a three-necked flask and frozen and pumped three times to remove oxygen. Stir and heat to 110℃ for condensation reflux for 24h, and cool after the constant temperature reaction; dilute the mixture with 100mL of dichloromethane and wash three times with 100mL of deionized water. The organic layer was dried with anhydrous magnesium sulfate, and then the anhydrous magnesium sulfate was removed by filtration. The filtrate was vacuum concentrated to obtain a crude product, and finally the crude product was purified by silica gel column chromatography with a yield of 52.1%.

[0110] Synthesis of pyridine-containing terphenyl diamine monomer 6F-MPTPDA: 3 g of NM-5, 60 mL of anhydrous ethanol and 0.68 g of Pd / C were added to a three-necked flask, and the temperature was stirred and heated to 80° C. under nitrogen conditions for condensation and reflux. The temperature was maintained, and 6.32 mL of hydrazine hydrate was added dropwise to the mixed solution in the three-necked flask using a constant pressure funnel (the dropping speed was one drop every two seconds). After the addition was completed, the temperature was maintained for 12 hours. After the constant temperature reaction was completed, the heating was stopped, and the Pd / C was removed by hot filtration. The filtrate was poured into cold water, and sodium chloride was added while stirring until a solid was precipitated. The solid was filtered out and washed with an ethanol\water mixed solution, and then the filtered solid was vacuum dried to obtain the pyridine-containing terphenyl diamine monomer 6F-MPTPDA;

[0111] Synthesis of polyimide 6FDA-6F-MPTPDA: Under a nitrogen atmosphere, 10 mmol of 6F-MPTPDA and 10 mmol of 6FDA were put into a three-necked flask, 32 mL of m-cresol and 8 mL of toluene were added, the temperature was raised to 80°C, and 4 mL of isoquinoline was added after constant stirring for 1 h. The temperature was then raised to 180°C and constant stirring was performed for 10 h. After the constant temperature reaction was completed, the mixture was cooled to room temperature, poured into 100 mL of methanol to precipitate a solid, filtered out the solid and washed with hot methanol, and the filtered solid was vacuum dried to obtain 6FDA-6F-MPTPDA.

[0112] High temperature film formation by blade coating: 1.2 g of 6FDA-6F-MPTPDA was dissolved in 6.8 g of DMAc, and then centrifuged for degassing (5000 r min -1 The film was formed by scraping and then coating in a vacuum oven at high temperature. The heating time was successively at 80° C. for 1 h, 150° C. for 2 h, 200° C. for 2 h and 220° C. for 2 h.

[0113] Example 6

[0114] Synthesis of pyridine-containing terphenyl diamine 6H-MPTPDA monomer:

[0115] Synthesis of pyridine-containing terphenyl dinitro monomer NM-6: 6mmol of M3, 2mmol of 3,5-dibromo-4-methylpyridine, 27mmol of potassium carbonate, 8mL of deionized water, 0.3mmol of tetrakis(triphenylphosphine)palladium, 4mL of ethanol and 8mL of toluene were placed in a three-necked flask and frozen and pumped 3 times to remove oxygen. Stir and heat to 110℃ for condensation reflux for 24h, and cool after the constant temperature reaction; dilute the mixture with 100mL of dichloromethane and wash three times with 100mL of deionized water. The organic layer was dried with anhydrous magnesium sulfate, and then the anhydrous magnesium sulfate was removed by filtration. The filtrate was vacuum concentrated to obtain a crude product, and finally the crude product was purified by silica gel column chromatography with a yield of 65.4%.

[0116] Synthesis of pyridine-containing terphenyl diamine monomer 6H-MPTPDA: 3 g of NM-6, 60 mL of anhydrous ethanol and 0.68 g of Pd / C were added to a three-necked flask, and the temperature was stirred and heated to 80° C. under nitrogen conditions for condensation and reflux. The temperature was maintained, and 6.32 mL of hydrazine hydrate was added dropwise to the mixed solution in the three-necked flask using a constant pressure funnel (the dropping speed was one drop every two seconds). After the addition was completed, the temperature was maintained for 12 hours. After the constant temperature reaction was completed, the heating was stopped, and the Pd / C was removed by hot filtration. The filtrate was poured into cold water, and sodium chloride was added while stirring until a solid was precipitated. The solid was filtered out and washed with an ethanol\water mixed solution, and then the filtered solid was vacuum dried to obtain the pyridine-containing terphenyl diamine monomer 6H-MPTPDA;

[0117] Synthesis of polyimide 6FDA-6H-MPTPDA: Under a nitrogen atmosphere, 10 mmol of 6H-MPTPDA and 10 mmol of 6FDA were put into a three-necked flask, 32 mL of m-cresol and 8 mL of toluene were added, the temperature was raised to 80°C, and 4 mL of isoquinoline was added after constant stirring for 1 h. The temperature was then raised to 180°C and constant stirring was performed for 10 h. After the constant temperature reaction was completed, the mixture was cooled to room temperature, poured into 100 mL of methanol to precipitate a solid, filtered out the solid and washed with hot methanol, and the filtered solid was vacuum dried to obtain 6FDA-6H-MPTPDA.

[0118] High temperature film formation by blade coating: 1.2 g of 6FDA-6H-MPTPDA was dissolved in 6.8 g of DMAc, and then centrifuged for degassing (5000 r min -1 The film was formed by scraping and then coating in a vacuum oven at high temperature. The heating time was successively at 80° C. for 1 h, 150° C. for 2 h, 200° C. for 2 h and 220° C. for 2 h.

[0119] Table 1 Performance test of polyimide prepared in Examples 1-6 after high temperature film formation by blade coating

[0120]

[0121] In Table 1, the linear thermal expansion coefficient test method: using a thermomechanical analyzer, 5℃min -1 , 50~200℃ test;

[0122] Glass transition temperature: using dynamic thermomechanical analyzer, 5℃min -1 , 1Hz, 30~400℃ test;

[0123] Optical transmittance: tested with UV spectrophotometer;

[0124] Tensile strength: GB / T 13542.6-2006 standard requires testing.

[0125] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A terphenyl diamine containing pyridine, characterized in that: Its structural formula is as shown in formula (1): In the formula, R1 is trifluoromethyl, methyl or fluoro; R2 is hydrogen or methyl.

2. The method for preparing the pyridine-containing terphenyl diamine according to claim 1, characterized in that The following steps are involved: S1. Place a bromine-substituted 4-nitrobenzene compound, bipyraclostrobin, potassium acetate, 1,1'-bis(diphenylphosphino)ferrocenepalladium dichloride, and 1,4-dioxane in a reaction vessel, stir and heat to 80-90° C. under inert gas conditions, and condense and reflux for 21-24 hours to obtain a monomer M; S2. Monomer M, a dibromo-substituted pyridine compound, potassium carbonate, water, tetrakis(triphenylphosphine)palladium, ethanol and toluene are placed in a reaction vessel, and under inert gas conditions, the temperature is raised to 100 to 120° C. with stirring and condensed under reflux for 20.5 to 24 hours to obtain a terphenyl dinitro monomer containing pyridine; S3. Under room temperature, add pyridine-containing terphenyl dinitro monomer, anhydrous ethanol and Pd / C into a reaction vessel. Under inert gas conditions, stir and heat to 80°C for condensation reflux. Add hydrazine hydrate dropwise to the mixed solution in the reaction vessel. After the addition is complete, maintain the temperature at 80°C for 10 to 12 hours to obtain the pyridine-containing terphenyl diamine.

3. The method according to claim 2, characterized in that The bromine-substituted 4-nitrobenzene compound in step S1 is 1-bromo-2-fluoro-4-nitrobenzene, 2-bromo-5-nitrotoluene or 2-bromo-5-nitrotrifluorotoluene; the dibromo-substituted pyridine compound in step S2 is 3,5-dibromopyridine or 3,5-dibromo-4-methylpyridine.

4. The method according to claim 2, characterized in that: In step S1, the molar ratio of the bromine-substituted 4-nitrobenzene compound, pinacol diboron, potassium acetate, and 1,1'-bis(diphenylphosphino)ferrocenepalladium dichloride is 10 mmol:12 mmol:32.24 mmol:0.21 mmol.

5. The method according to claim 2, characterized in that: In step S2, the molar ratio of the monomer M, the bromine-substituted pyridine compound, potassium carbonate and tetrakis(triphenylphosphine)palladium is 3:1:13.5:0.

15.

6. The method according to claim 2, characterized in that In step S3, the ratio of the pyridine-containing terphenyl dinitro monomer, Pd / C and anhydrous ethanol is 3 g:0.68 g:60 mL; the ratio of the pyridine-containing terphenyl dinitro monomer and hydrazine hydrate is 3 g:6.32 mL; In step S3, the dripping speed of the hydrazine hydrate is one drop every two seconds.

7. A polyimide, characterized in that: It includes the following repeating units: Among them, R1 is fluoro, trifluoromethyl or methyl, R2 is hydrogen or methyl, and n is 43-77.

8. The method for preparing the polyimide according to claim 7, characterized in that: The method comprises the following steps: placing the pyridine-containing terphenyl diamine monomer, tetracarboxylic dianhydride monomer and m-cresol in a reaction container, heating the container to 60-80° C., stirring the container at a constant temperature for 0.5-1 hour, adding a catalyst, and then heating the container to 180-185° C. and stirring the container at a constant temperature for 8-10 hours to obtain the polyimide; The tetracarboxylic dianhydride monomer structural formula is as follows:

9. The method according to claim 8, characterized in that The molar ratio of the tetracarboxylic dianhydride monomer to the pyridine-containing terphenyl diamine monomer is 1:1; The catalyst is isoquinoline.

10. Use of the polyimide according to claim 7 in the field of flexible electronics.

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