A diamine monomer containing a fully trans-substituted cyclobutane structure and its use in high-performance transparent polyimides

Abstract

The application provides a diamine monomer containing a fully trans-substituted cyclobutane structure and application thereof in high-performance transparent polyimide, and belongs to the field of high-performance polymer materials and manufacture of intermediates. The diamine monomer containing a fully trans-substituted cyclobutane structure has a structure as shown in formula IV (each group is defined as described in the specification), and the preparation method of the diamine monomer is simple, green, and efficient. The polyimide prepared from the diamine monomer has good solubility and is easy to process, and can be used to prepare a flexible transparent polyimide film with heat resistance, weather resistance, low water absorption, and low dielectric constant, and is suitable for use in the fields of packaging materials for the electronic and electrical industries and flexible display.

Description

Technical Field

[0001] The present invention belongs to the field of manufacturing high-performance polymer materials and intermediates thereof, and specifically relates to a diamine monomer containing an all-trans-substituted cyclobutane structure and application thereof in high-performance transparent polyimide. Background Art

[0002] Polyimide is used in a variety of fields such as aerospace, electronics, and microelectronics due to its excellent heat resistance, film-forming properties, mechanical stability, and electrical insulation. However, the formation of charge transfer complexes within and between polyimide molecular chains often gives this material a darker gloss and poor transparency. In recent years, with the rapid development of emerging electronic technology industries such as high-frequency communication technology, flexible displays, and smart wearables, higher requirements have been placed on the transparency of polyimide dielectric film materials. The design and development of high-performance transparent polyimides has received widespread attention from scientific and technological workers. Numerous research results have shown that the introduction of rigid and bulky side groups, fluorine-containing groups, alicyclic structures, etc. into the polyimide molecular chain can help weaken the charge transfer interaction and thus improve the transparency of the polyimide film material. In addition, increasing the twist of the polyimide molecular chain can help reduce the polymer molecular chain stacking effect and improve the transparency and solubility of the polyimide material. Summary of the Invention

[0003] The present invention aims to provide a diamine monomer containing a fully trans-substituted cyclobutane structure and its application in high-performance transparent polyimide. The polyimide prepared by the polycondensation reaction of the diamine monomer containing a fully trans-substituted cyclobutane structure provided by the present invention and a commercial dianhydride monomer exhibits high transparency and solubility, as well as good film-forming properties, thermal stability, and a low dielectric constant.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] In a first aspect of the present invention, a diamine monomer containing an all-trans-substituted cyclobutane structure is provided, having a structure as shown in Formula IV:

[0006]

[0007] The second aspect of the present invention provides a method for preparing a diamine monomer containing an all-trans-substituted cyclobutane structure, comprising the following steps:

[0008] (a) subjecting the following compound having a structure represented by Formula I to a nucleophilic substitution reaction with the following halogenated amide having a structure represented by Formula II in the presence of an inorganic base to form the following compound having a structure represented by Formula III;

[0009]

[0010] Wherein, R1 and R2 are each independently selected from the following group: H, methyl, and X is a halogen selected from the following group: Cl, Br, I.

[0011] (b) reacting a compound having a structure represented by Formula III in an organic solvent at a high temperature in the presence of a strong base to form a compound having a structure represented by Formula IV;

[0012]

[0013] Preferably, the reaction in step (a) is carried out in the presence of an inorganic base selected from the group consisting of potassium carbonate, potassium hydroxide, cesium carbonate, sodium hydride, or a combination thereof; the molar ratio of the compound of formula I to the halogenated amide of formula II is 1:2-4; and the molar ratio of the compound of formula I to the inorganic base is 1:2-5.

[0014] Preferably, the reaction in step (b) is carried out in the presence of a strong base selected from the group consisting of potassium carbonate, potassium hydroxide, cesium carbonate, sodium hydride, or a combination thereof; the organic solvent is dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone; and the molar ratio of the compound represented by formula III to the base is 1:2-5.

[0015] In a third aspect of the present invention, a polyimide is provided having a structure as shown in Formula V:

[0016]

[0017] The value range of n is n≥10;

[0018] X is One or more of .

[0019] A fourth aspect of the present invention provides a method for preparing a polyimide film, comprising the following steps:

[0020] (1) Under an inert gas atmosphere, a diamine monomer having a structure represented by Formula IV, a dianhydride monomer, and an organic solvent are mixed and polycondensed to obtain a homogeneous and transparent polyamic acid solution;

[0021] (2) adding acetic anhydride and triethylamine to the polyamic acid solution obtained in step (1), and obtaining a homogeneous and transparent polyimide solution through dehydration reaction;

[0022] (3) The polyimide solution obtained in step (2) is precipitated in a large amount of methanol to obtain a polyimide having a structure shown in formula IV.

[0023] (4) dissolving the polyimide obtained in step (3) in an organic solvent to obtain a polyimide solution, casting the polyimide solution onto a glass plate, and slowly removing the solvent at a certain temperature to obtain a polyimide film.

[0024] Preferably, the molar ratio of the diamine monomer having the structure represented by Formula IV to the dianhydride monomer in step (1) is 1:1-1.02.

[0025] Preferably, the organic solvent in step (1) is one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone, and the dianhydride monomer is 4,4'-(hexafluoroisopropylene) diphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic anhydride, 4,4'-oxydiphthalic anhydride, or 4,4'-benzophenonetetracarboxylic anhydride.

[0026] Preferably, the organic solvent in step (4) is N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone.

[0027] The present invention also provides application of the polyimide film in transparent dielectric materials.

[0028] Beneficial effects of the present invention

[0029] The present invention provides a diamine monomer containing a fully trans-substituted cyclobutane structure and its use in high-performance transparent polyimides. The diamine monomer provided herein contains a fully trans-substituted cyclobutane structure and has a large twisted dihedral angle. Polyimides prepared using this unique diamine monomer exhibit a highly twisted molecular chain structure, reducing molecular chain stacking, thereby significantly improving the solubility and transparency of the polyimide material. This twisted structure also increases the free volume of the polymer chain, significantly reducing the dielectric constant and dielectric loss of the polymer at high frequencies. Experimental results show that the diamine monomer containing a fully trans-substituted cyclobutane structure provided by the present invention can be used to prepare transparent polyimide films with low dielectric constant, low dielectric loss, and excellent thermal stability. For example, the polyimide 6FDA-PI has a dielectric constant of 2.43 at 10 GHz, a dielectric loss factor of 0.003, a transmittance of 92% at 400 nm, a 5% thermal weight loss temperature of 490°C in nitrogen, and a linear thermal expansion coefficient as low as 56 ppm / °C below 300°C.

[0030] The polyimide film provided by the invention has good solubility and is easy to process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Attachment Figure 1 The product obtained by Example 3 of the present invention 1 H NMR spectrum. DETAILED DESCRIPTION

[0033] The present invention provides a diamine monomer containing an all-trans-substituted cyclobutane structure, having a structure as shown in Formula IV:

[0034]

[0035] The present invention provides a method for preparing a diamine monomer containing an all-trans-substituted cyclobutane structure, comprising the following steps:

[0036] (a) In an acetonitrile solvent, a compound having a structure represented by Formula I and a haloamide having a structure represented by Formula II are subjected to a nucleophilic substitution reaction at 80° C. in the presence of an inorganic base, wherein the base is preferably potassium iodide, potassium carbonate, potassium hydroxide, cesium carbonate, sodium hydride, or a combination thereof; the reaction time is preferably 12-24 hours, and the crude product is purified by recrystallization using dichloromethane and petroleum ether to form a compound having a structure represented by Formula III;

[0037]

[0038] Wherein, R1 and R2 are each independently selected from the following group: H, methyl, and X is a halogen selected from the following group: Cl, Br, I.

[0039] (b) reacting the compound having the structure shown in Formula III in an organic solvent at 140° C. in the presence of a strong base, wherein the strong base is potassium carbonate, potassium hydroxide, cesium carbonate, sodium hydride, or a combination thereof; and the organic solvent is dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, or N-methylpyrrolidone; and the reaction time is preferably 24-48 hours to form the compound having the structure shown in Formula IV below;

[0040]

[0041] Wherein, R1 and R2 are each independently selected from the following group: H, methyl, and X is a halogen selected from the following group: Cl, Br, I.

[0042]

[0043] The present invention also provides a polyimide having a structure as shown in Formula V:

[0044]

[0045] In formula V, the value range of n is n≥20;

[0046] X is One or more of .

[0047] Preferably, the structural formula of the polyimide is as follows:

[0048]

[0049] The present invention also provides a method for preparing a polyimide film, comprising the following steps:

[0050] (1) Under an inert gas atmosphere, a diamine monomer having a structure shown in Formula IV, a dianhydride monomer and an organic solvent are mixed and subjected to a condensation reaction. The reaction temperature is preferably 20-40° C. and the reaction time is preferably 12-48 hours to obtain a homogeneous transparent polyamic acid solution. The molar ratio of the diamine monomer having a structure shown in Formula IV to the dianhydride monomer is 1:1-1.02. The sum of the molar amounts of the diamine monomer having a structure shown in Formula IV and the dianhydride monomer is 20%-50% of the volume of the solvent used. The organic solvent is preferably one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone. The dianhydride monomer is preferably 4,4'-(hexafluoroisopropylene) diphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic anhydride, 4,4'-oxydiphthalic anhydride or 4,4'-benzophenonetetracarboxylic anhydride.

[0051] (2) adding acetic anhydride and triethylamine to the polyamic acid solution obtained in step (1), and subjecting the mixture to a dehydration reaction, wherein the reaction temperature is preferably 20-40° C. and the reaction time is preferably 12-48 hours, to obtain a homogeneous and transparent polyimide solution; wherein the amount of acetic anhydride is 1-2 times the sum of the amounts of the diamine monomer and the dianhydride monomer; and the amount of triethylamine is 1-2 times the sum of the amounts of the diamine monomer and the dianhydride monomer.

[0052] (3) The polyimide solution obtained in step (2) is precipitated in a large amount of methanol to obtain a polyimide having a structure shown in Formula V.

[0053] (4) dissolving the polyimide obtained in step (3) in an organic solvent to obtain a polyimide solution, wherein the organic solvent is preferably N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone; casting the polyimide solution onto a glass plate, slowly removing the solvent at a certain temperature, preferably 60-100°C, for preferably 12-48 hours, and naturally cooling to room temperature to obtain a polyimide film.

[0054] The polyimide film is immersed in deionized water and separated from the glass plate to obtain a polymer film, which is then vacuum dried to obtain a transparent polyimide film; the vacuum drying temperature is preferably 60-100° C., and the time is preferably 6-8 hours.

[0055] The present invention also provides application of the polyimide film in high-frequency and low-dielectric-constant materials.

[0056] The present invention is further described in detail below with reference to specific examples, in which the raw materials involved are all commercially available.

[0057] Example 1 Preparation of diamine monomer containing dipropionamide structure

[0058]

[0059] In a 250ml round-bottom flask equipped with a magnetic rod, (1S,2S,3R,4R)-1,2-bis(4-hydroxyphenyl)-3,4-dimethylcyclobutane (4.4362g, 0.0165mol, 1equiv) and 2-bromopropionamide (5.0251g, 0.033mol, 2equiv) were dissolved in acetonitrile (150ml). Potassium iodide (0.2744g, 0.1equiv) and potassium carbonate (6.8488g, 0.496mol, 3equiv) were added. The reaction mixture was heated to 80°C and refluxed for 36 hours. After cooling to room temperature, the solvent was removed by distillation under reduced pressure. The mixture was extracted twice with ethyl acetate and washed with saturated brine. Drying over anhydrous sodium sulfate, filtration, and removal of the solvent yielded the crude product. The product was recrystallized with dichloromethane / petroleum ether (DCM:Pe=1:20) to obtain a diamine monomer containing a dipropionamide structure (6.43 g, yield 95%).

[0060] Example 2 Preparation of diamine monomer containing dibutyramide structure

[0061]

[0062] In a 250ml round-bottom flask equipped with a magnetic rod, (1S,2S,3R,4R)-1,2-bis(4-hydroxyphenyl)-3,4-dimethylcyclobutane (2.6836g, 0.01mol, 1equiv) and 2-bromoisobutyramide (3.3204g, 0.02mol, 2equiv) were dissolved in acetonitrile (100ml). Potassium iodide (0.166g, 0.1equiv) and potassium carbonate (3.3204g, 0.03mol, 3equiv) were added. The reaction mixture was heated to 80°C and refluxed for 36 hours. After cooling to room temperature, the solvent was removed by distillation under reduced pressure. The mixture was extracted twice with ethyl acetate and washed with saturated brine. Drying over anhydrous sodium sulfate, filtration, and solvent removal were performed to obtain a crude product. Recrystallize with dichloromethane / petroleum ether (DCM:Pe=1:20) to obtain a diamine monomer containing a dibutylamide structure (6.43 g, yield 95%)

[0063] Example 3 Preparation of diamine monomer containing all-trans-substituted cyclobutane structure

[0064]

[0065] A four-membered aromatic derivative (6.8680 g, 1 equiv) and potassium hydroxide (2.2526 g, 40.15 mmol, 2.4 equiv) were dissolved in DMSO (58 ml). The reaction mixture was heated to 140°C, refluxed for 18 hours, cooled to room temperature, and diluted with water. The product was extracted three times with ethyl acetate and washed with saturated brine. The product was dried over anhydrous magnesium sulfate, filtered, and the solvent removed to obtain a crude product. Column chromatography using dichloromethane / methanol (DCM:MeOH = 50:1) as the eluent afforded the diamine monomer containing the all-trans-substituted cyclobutane structure (after column chromatography and recrystallization, 1.10104 g, yield 22.39%).

[0066] Example 4 Preparation of 6FDA-PI

[0067] Under argon protection, a mixture of 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA) (223.9 mg, 0.5 mmol), a diamine monomer containing a fully trans-substituted cyclobutane structure (134.1 mg, 0.5 mmol), and N-methylpyrrolidone (1.5 mL) was reacted at 25 ° C for 24 hours, and then acetic anhydride (0.4 mL) and triethylamine (0.2 mL) were added. After stirring at 25 ° C for 24 hours, the reaction solution was slowly added dropwise to methanol (400 mL). A white filamentous solid was obtained by filtration. After vacuum drying at 70 ° C for 6 hours, polyimide 6FDA-PIA was obtained.

[0068] The structure of the polyimide 6FDA-PI containing an all-trans-substituted cyclobutane structure is as follows:

[0069]

[0070] Example 5 Preparation of ODPA-PI

[0071] Under argon protection, a mixture of 4,4'-oxydiphthalic anhydride (ODPA) (310.21 mg, 1 mmol), a diamine monomer containing a fully trans-substituted cyclobutane structure (268.2 mg, 1 mmol), and N-methylpyrrolidone (3 mL) was reacted at 25 ° C for 24 hours, and then acetic anhydride (0.8 mL) and triethylamine (0.4 mL) were added. After stirring at 25 ° C for 24 hours, the reaction solution was slowly added dropwise to methanol (600 mL). After filtration, a white filamentous solid was obtained, which was vacuum dried at 70 ° C for 6 hours to obtain polyimide ODPA-PI.

[0072] The structure of the polyimide ODPA-PI containing an all-trans-substituted cyclobutane structure is as follows:

[0073]

[0074] Example 6 Preparation of PMDA-PI

[0075] Under argon protection, a mixture of pyromellitic dianhydride (PMDA) (218.12 mg, 1 mmol), a diamine monomer containing a fully trans-substituted cyclobutane structure (268.2 mg, 1 mmol), and N-methylpyrrolidone (3 mL) was reacted at 25°C for 24 hours. Then, acetic anhydride (0.8 mL) and triethylamine (0.4 mL) were added. After stirring at 25°C for 24 hours, the reaction solution was slowly added dropwise to methanol (600 mL). After filtration, a white filamentous solid was obtained. After vacuum drying at 70°C for 6 hours, polyimide PMDA-PI was obtained.

[0076] The structure of the polyimide PMDA-PI containing an all-trans-substituted cyclobutane structure is as follows:

[0077]

[0078] Example 7 Preparation of HPMDA-PI

[0079] Under argon protection, a mixture of 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA) (224.17 mg g, 1 mmol), a diamine monomer containing an all-trans-substituted cyclobutane structure (268.2 mg, 1 mmol), and N-methylpyrrolidone (3 mL) was reacted at 25°C for 24 hours. Then, acetic anhydride (0.8 mL) and triethylamine (0.4 mL) were added. After stirring at 25°C for 24 hours, the reaction solution was slowly added dropwise to methanol (600 mL). A white filamentous solid was obtained by filtration. The solid was dried in vacuo at 70°C for 6 hours to obtain polyimide HPMDA-PI.

[0080] The structure of the polyimide HPMDA-PI containing an all-trans-substituted cyclobutane structure is as follows:

[0081]

[0082] Example 8 Preparation of BTDA-PI

[0083] Under argon protection, a mixture of 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) (224.17 mg g, 1 mmol), a diamine monomer containing an all-trans-substituted cyclobutane structure (268.2 mg, 1 mmol), and N-methylpyrrolidone (3 mL) was reacted at 25°C for 24 hours. Then, acetic anhydride (0.8 mL) and triethylamine (0.4 mL) were added. After stirring at 25°C for 24 hours, the reaction solution was slowly added dropwise to methanol (600 mL). A white filamentous solid was obtained by filtration. After vacuum drying at 70°C for 6 hours, polyimide BTDA-PI was obtained.

[0084] The structure of the polyimide BTDA-PI containing an all-trans-substituted cyclobutane structure is as follows:

[0085]

[0086] Example 9 Preparation of BPDA-PI

[0087] Under argon protection, a mixture of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) (294.88 mg g, 1 mmol), a diamine monomer containing an all-trans-substituted cyclobutane structure (268.2 mg, 1 mmol), and N-methylpyrrolidone (3 mL) was reacted at 25°C for 24 hours. Then, acetic anhydride (0.8 mL) and triethylamine (0.4 mL) were added. After stirring at 25°C for 24 hours, the reaction solution was slowly added dropwise to methanol (600 mL). After filtration, a white filamentous solid was obtained, which was dried in vacuo at 70°C for 6 hours to obtain polyimide BPDA-PI.

[0088] The structure of the polyimide BPDA-PI containing an all-trans-substituted cyclobutane structure is as follows:

[0089]

[0090] Example 10

[0091] 6FDA-PI (1 g) was dissolved in 15 mL of N,N-dimethylacetamide to form a homogeneous transparent solution. The obtained solution was cast onto a clean glass plate, dried at 80°C for 12 h, and naturally cooled to room temperature to obtain a 6FDA-PI film.

[0092] ODPA-PI (1 g) was dissolved in 15 mL of N,N-dimethylacetamide to form a homogeneous transparent solution. The obtained solution was cast onto a clean glass plate, dried at 80°C for 12 h, and naturally cooled to room temperature to obtain an ODPA-PI film.

[0093] BPDA-PI (1 g) was dissolved in 15 mL of N,N-dimethylacetamide to form a homogeneous transparent solution. The obtained solution was cast onto a clean glass plate, dried at 80°C for 12 h, and naturally cooled to room temperature to obtain a BPDA-PI film.

[0094] PMDA-PI (1 g) was dissolved in 15 mL of N,N-dimethylacetamide to form a homogeneous transparent solution. The obtained solution was cast onto a clean glass plate, dried at 80°C for 12 h, and naturally cooled to room temperature to obtain a PMDA-PI film.

[0095] The thermal stability of the obtained film was tested by TGA, with nitrogen as the carrier gas and a heating rate of 10°C / min; the linear thermal expansion coefficient was tested by thermomechanical analysis, with a heating rate of 5°C / min; the transmittance of the film was tested by UV-visible spectrophotometer; and the dielectric properties were tested by Agilent impedance meter and network spectrum analyzer.

[0096]

[0097] All documents mentioned in this application are incorporated herein by reference, just as if each document were incorporated herein by reference individually. Furthermore, it should be understood that, after reading the above disclosure, any modifications made to the technical solution of the present invention by those skilled in the art should be within the scope of protection defined by the claims.

Claims

1. A diamine monomer containing an all-trans-substituted cyclobutane structure, characterized in that: It has the structure shown in Formula IV:

2. The method for preparing a diamine monomer containing an all-trans-substituted cyclobutane structure according to claim 1, wherein: The following steps are involved: (a) reacting a compound having a structure shown in Formula I with a halogenated amide having a structure shown in Formula II in the presence of an inorganic base to form a compound having a structure shown in Formula III; wherein R1 and R2 are each independently selected from the group consisting of H, methyl, and X is a halogen selected from the group consisting of Cl, Br, and I; (b) reacting a compound having a structure represented by Formula III in an organic solvent at a high temperature in the presence of a strong base to form a compound having a structure represented by Formula IV; 3. The method for preparing a diamine monomer containing an all-trans-substituted cyclobutane structure according to claim 2, wherein: The reaction in step (a) is carried out in the presence of an inorganic base selected from the group consisting of potassium carbonate, potassium hydroxide, cesium carbonate, sodium hydride, or a combination thereof; the molar ratio of the compound of formula I to the halogenated amide of formula II is 1:2-4; and the molar ratio of the compound of formula I to the inorganic base is 1:2-5.

4. The method for preparing a diamine monomer containing an all-trans-substituted cyclobutane structure according to claim 2, wherein: The reaction in step (b) is carried out in the presence of a strong base selected from the group consisting of potassium carbonate, potassium hydroxide, cesium carbonate, sodium hydride, or a combination thereof; the organic solvent is dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, or N-methylpyrrolidone; and the molar ratio of the compound of formula III to the base is 1:2-5.

5. A polyimide, characterized in that It has the structure shown in formula V: The value range of n is n≥10; X is One or more of .

6. The method for preparing a polyimide according to claim 5, wherein: The following steps are involved: (1) Under an inert gas atmosphere, a diamine monomer having a structure of Formula IV as claimed in claim 1, a dianhydride monomer, and an organic solvent are mixed and polycondensed to obtain a homogeneous transparent polyamic acid solution; (2) adding acetic anhydride and triethylamine to the polyamic acid solution obtained in step (1), and obtaining a homogeneous and transparent polyimide solution through dehydration reaction; (3) The polyimide solution obtained in step (2) is precipitated in a large amount of methanol to obtain a polyimide having a structure shown in formula IV.

7. The method for preparing a polyimide according to claim 6, wherein: The molar ratio of the diamine monomer having the structure shown in Formula IV to the dianhydride monomer in step (1) is 1:1-1.02; the organic solvent is N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone.

8. A method for preparing a polyimide film, characterized in that: The method comprises the following steps: dissolving the polyimide obtained in step (3) of claim 6 in an organic solvent to obtain a polyimide solution, casting the polyimide solution onto a glass plate, and slowly removing the solvent at 60-100° C. to obtain a polyimide film.

9. The method for preparing a polyimide film according to claim 8, wherein: The organic solvent in the step is N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone.

10. Use of the polyimide film according to claim 8 in transparent dielectric materials.

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