A fluorinated polyetherimide containing a carbazole structure and a method for preparing the same

Abstract

The application discloses fluorinated polyether imide containing a carbazole structure and a preparation method thereof, and belongs to the technical field of modified polyimide materials. The fluorinated polyether imide containing the carbazole structure has the following repeating structural units: by introducing the carbazole structural unit containing a trifluoromethyl group, an ether bond, a large molecular volume and an asymmetric polar structure into a main chain, the fluorinated polyether imide containing the carbazole structure is endowed with good comprehensive properties such as solubility, heat resistance, optical performance, mechanical performance, dielectric performance and hydrophobicity.

Description

Technical Field

[0001] This invention relates to a polyetherimide, particularly a fluorinated carbazole-containing polyetherimide, and also to its preparation method, belonging to the field of polymer materials technology. Background Technology

[0002] Polyimide (PI) possesses excellent properties such as high temperature resistance, chemical corrosion resistance, and abrasion resistance, attracting widespread attention in aerospace, microelectronics, and separation membrane fields. However, these materials still have some inherent drawbacks in practical applications, the most prominent being the poor solubility and refractory nature of aromatic polyimides. This characteristic severely restricts the material's processing performance and application range. Given the relatively limited variety of functional materials and the long development cycle and high cost of novel PI research, molecular structure modification of existing polyimide materials has become a more economical research direction.

[0003] To date, researchers have mainly studied the modification of polyimides from the following aspects: (1) Introducing flexible structural units. Introducing a suitable amount of flexible groups (such as ether bonds, methyl groups, etc.) can improve the packing density of molecular chains and also hinder the formation of charge transfer complexes (CTCs), thereby improving the solubility and optical transparency of PIs. For example, the literature (“Preparation and properties of highly organosoluble polyimides derived from 2,2'-disubstituted-4,4'-oxydianilines”, Zhao J, et al. High Performance Polymers, 2017, 30(4): 456-464) discloses a series of polyimide PIs. Due to the introduction of ether bonds, the orientation and flexibility of the polymer molecular chains are affected, hindering the close packing of molecular chains, which makes PIs have good solubility. At the same time, due to the presence of rigid biphenyl or naphthalene, PIs have good thermal stability and are expected to be candidate materials in the electronic field. (2) Introducing a twisted non-coplanar structure: By introducing a twisted non-coplanar structure, the molecular configuration can be effectively changed, hindering the stacking of PI molecular chains and effectively disrupting the formation of CTC, thereby improving the overall performance of the material, including improving solubility, enhancing melt processing performance, and optimizing optical transparency. For example, the literature (“Synthesis and optoelectronic properties of polyimides with naphthyldiphenyl-amine chromophores”, Hsiao SH, et al. Journal of Polymer Research, 2014, 21(4):407) discloses the synthesis of a series of electroactive polyimides containing naphthyldiphenylamine units using N,N'-bis(4-aminophenyl)-N,N'-bis2-naphthyl-1,4-phenylenediamine and four tetracarboxylic acid dianhydrides as raw materials. Since triphenylamine is a twisted non-coplanar structure, PIs are easily soluble in many organic solvents and can be cast into tough amorphous films. Due to the rigidity of naphthalene, it also exhibits good thermal properties, T gThe temperature range is 288-329℃, and there is no significant decomposition before 500℃. (3) Introducing large-volume side group units: Introducing large-volume side groups into the PI molecular chain effectively reduces the stacking of the molecular chain. At the same time, this structural modification can suppress chain segment movement and improve the rigidity of the molecular chain. For example, the literature (“Fabrication and characterization of novel high-performance fluorinated polyimides with xanthene pendent architecture: Study of thermal, photophysical, antibacteria and heavy metal ion adsorption behavior”, Amininasab SM, et al. Journal of Fluorine Chemistry, 2016, 192: 48-57) discloses a series of high-performance fluorinated polyimides with xanthene side chains with different functional groups. These polymers PIs show good solubility and thermal stability, and have a high glass transition temperature T g(235~303℃) and 10% weight loss (402~498℃), with more than 62% residue at 800℃ and N2 atmosphere. This is due to the presence of functional groups such as ether bonds and large-volume side groups such as -CF3, substituted imidazole, and xaton on its main chain, which improves the solubility of the polymer while maintaining thermal stability. (4) Introduction of alicyclic structure: The introduction of alicyclic structure can hinder the packing density of molecular chains and inhibit CTC effect. Therefore, the introduction of alicyclic structure can make the polymer have good solubility and optical transparency. For example, the literature (“Synthesis and properties of polyimides derived from bis-(aminophenoxy)containing naphthalene,[phenyl]propane and[methyl]cyclohexane segment and 4,4'-carbonyldiphthalic anhydride”, Mirsamiei A, Journal of Macromolecular Science, Part A, 2018, 55(7):519-525) discloses the synthesis of three fully aromatic, semi-aromatic, and aliphatic-aromatic polyimides, respectively containing naphthalene, phenylpropane, and cyclohexane structures, through a two-step chemical and thermal imidization reaction using bis(ether-amine) and 4,4'-carbonyldiphthalic anhydride (CDPA) as raw materials. Tests show that the polyimide containing the cyclohexane segment exhibits better transparency, lower dielectric constant, and hygroscopicity, making it suitable for applications in optoelectronics and microelectronics. (5) Introduction of Fluorine-containing Structures: Studies have shown that fluorine atoms have small atomic radii and high electronegativity, which can effectively reduce the polarization and packing density of PI molecular chains to a certain extent. This not only improves the optical transparency of PI but also reduces the dielectric constant of PI films. It is worth noting that a simple fluorine substitution strategy can maximize the preservation of PI's thermal stability and mechanical strength without sacrificing the rigidity of the main chain and maintaining the tight packing of molecular chains. Compared with the substitution of a single fluorine atom, the introduction of trifluoromethyl groups produces more significant effects. -CF3, as a strong electron-withdrawing group, can improve the tight packing of PI by increasing the inter-chain gaps. This not only improves the solubility and light transmittance of PI but also significantly reduces its water absorption rate and dielectric constant due to its inherent hydrophobic properties, thus making this type of modified material have broad application prospects in the field of optoelectronic devices.For example, the literature (“Tristable data-storage device of soluble polyimides based on novel asymmetrical diamines containing carbazole”, Zhao J, et al. Polymer Chemistry, 2016, 7(9): 1765-1772) discloses the synthesis of a novel asymmetric diamine containing fluorine atoms using 9-(2-bromobenzyl)-3,6-diaminocarbazole as a raw material, followed by condensation with two dianhydrides in DMAc and chemical imidization to obtain two functional soluble polyimides. Due to the introduction of fluorine atoms, the polarizability and packing density of the polyimide molecular chain are effectively reduced, resulting in polymers with excellent organic solubility and high thermal stability, losing 5% of their weight under a nitrogen atmosphere above 300°C. Although there are many existing methods for modifying polyimides, these methods are all limited and lack diversity, making it difficult to effectively improve the overall performance of polyimides. Summary of the Invention

[0004] In view of the technical defects of the prior art, the first objective of the present invention is to provide a fluorinated carbazole-containing polyetherimide. The key to this polyetherimide is the introduction of a carbazole unit in the main chain that simultaneously contains trifluoromethyl, ether bond, large molecular volume and asymmetric polar structure, thereby endowing it with good comprehensive properties such as solubility, heat resistance, optical properties, mechanical properties, dielectric properties and hydrophobicity.

[0005] The second objective of this invention is to provide a method for preparing fluorinated carbazole-containing polyetherimide, which can be synthesized using a mature polymerization process, is simple and controllable to operate, and is beneficial for industrial production.

[0006] To achieve the above-mentioned technical objectives, the present invention provides a fluorinated carbazole-containing polyetherimide having the following repeating structural units:

[0007]

[0008] in,

[0009] Ar for

[0010] The key to the fluorinated carbazole-containing polyetherimide of the present invention lies in: designing special carbazole structural units and introducing them into the main chain of the polyimide molecular structure, thereby endowing it with good comprehensive properties. The carbazole structural unit has the following characteristics: (1) It has a flexible ether bond (–O–), which can disrupt the regularity of the aromatic polyimide molecular backbone, reduce the rigidity of the backbone structure, and improve the solubility and flexibility of polyimide; (2) It has a non-planar, asymmetric polar structure, which can disrupt the regularity of the aromatic polyimide backbone and impart polarity to it, thereby improving its solubility; (3) It introduces a trifluoromethyl side group, which can not only effectively prevent the close packing of polymer molecular chains and weaken its crystallization ability, but also improve its solubility, while imparting a low dielectric constant and improving its hydrophobic properties; (4) It has a large volume side group, which can reduce the regularity of the backbone, increase the spacing between polymer chains, thereby effectively reducing the packing degree of the backbone, weakening the interaction between and within the molecular chains, and the probability of CTC formation, thereby improving the solubility and light transmittance of polyimide. (5) Due to its inherent rigidity, carbazole is incorporated into the polyimide molecular chain, which effectively maintains the excellent heat resistance and mechanical strength of the polyimide material. In summary, this invention designs a carbazole structural unit containing ether bonds, trifluoromethyl groups, and large volume, and introduces it into the polyimide molecular backbone to endow polyimide with good comprehensive optical, electrical, and thermal properties.

[0011] As a preferred option, the number-average molecular weight of fluorinated carbazole-containing polyetherimide is 4 × 10⁻⁶. 4 ~6×10 4 Fluorinated carbazole-containing polyetherimides have a larger molecular weight and better film-forming and processing properties.

[0012] This invention also provides a method for preparing fluorinated carbazole-containing polyetherimide, comprising the following steps:

[0013] 1) The diamine monomer and the dianhydride monomer are subjected to a polycondensation reaction to obtain a polyamic acid intermediate;

[0014] 2) The polyamic acid intermediate is chemically imidized under the promoting action of acetic anhydride and pyridine to obtain fluorinated carbazole-containing polyetherimide;

[0015] The diamine monomer has the following molecular structure:

[0016]

[0017] The dianhydride monomer has the following molecular structure:

[0018]

[0019] Where Ar is

[0020] As a preferred embodiment, the polycondensation reaction is carried out under the following conditions: first, the reaction is carried out at a temperature of -5℃ to 5℃ for 0.5 to 1.5 hours, and then the reaction is carried out at room temperature with stirring for 12 to 14 hours.

[0021] As a preferred embodiment, the polycondensation reaction is carried out in anhydrous DMAc.

[0022] As a preferred embodiment, the amount of anhydrous DMAc used is such that the solid content of the polymerization system is maintained at 15-25%.

[0023] As a preferred embodiment, the conditions for chemical imidization are as follows: first, acetic anhydride and pyridine are added and stirred evenly at room temperature, and then the temperature is raised to 105-115°C and stirred for 4-6 hours.

[0024] Compared with existing technologies, the beneficial technical effects of the present invention are as follows:

[0025] This invention designs a carbazole structural unit that simultaneously possesses an ether bond, a trifluoromethyl side group, and a large molecular size. Introducing this unit into the polyetherimide molecule can significantly improve the overall physical properties of the polyetherimide.

[0026] (1) The fluorinated carbazole-containing polyetherimide backbone of the present invention contains ether bonds and trifluoromethyl structures, which effectively optimizes the flexibility of the molecular chain. Its tensile strength is 135.44~169.65MPa, and its elastic modulus can reach up to 3.00GPa. At the same time, the presence of rigid carbazole structure and imide bonds gives it good thermal stability, and its glass transition temperature (T) is low. g The temperature ranges from 273.5 to 341.9℃, and the temperature at T... 5％ The temperature ranges from 405.5 to 530.7℃.

[0027] (2) The fluorinated carbazole-containing polyetherimide of the present invention exhibits excellent dielectric properties, which is attributed to the incorporation of large-volume carbazole and trifluoromethyl in its main chain. These structures can increase the inter-chain spacing and free volume ratio, while reducing the proportion of polar groups in the molecular chain, thereby significantly reducing the dielectric constant of the polymer.

[0028] (3) The fluorinated carbazole-containing polyetherimide of the present invention has a λ0 of 362-385 nm, exhibiting good optical transparency. Attached Figure Description

[0029] Figure 1 Infrared spectra of fluorinated carbazole-containing polyetherimides PI-1 to PI-5.

[0030] Figure 2UV-Vis curves of fluorinated carbazole-containing polyetherimides PI-1 to PI-5.

[0031] Figure 3 TGA curves (a) and DMA curves (b) for fluorinated carbazole-containing polyetherimides PI-1 to PI-5.

[0032] Figure 4 Stress-strain curves for fluorinated carbazole-containing polyetherimides PI-1 to PI-5. Detailed Implementation

[0033] The following specific embodiments are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the claims.

[0034] The raw materials and reagents used in the following examples are all conventional commercially available products.

[0035] Testing and characterization methods:

[0036] (1) Fourier Transform Infrared Spectroscopy (FT-IR): Samples were prepared against a KBr background and measured using a Spectrum Two FT-IR spectroscopy unit. The wavenumber was set to 4000 to 400 cm⁻¹. -1 .

[0037] (2) Nuclear Magnetic Resonance Spectroscopy (NMR): Weigh approximately 2 mg and dissolve it in CDCl3 or DMSO-d6. Perform the spectroscopy using an Avance 400MHz or 600MHz NMR spectrometer. 1 H NMR and 13 C NMR test.

[0038] (3) Melting point test (MP): The melting point was determined using a micro melting point apparatus (FCE-3000).

[0039] (4) Solubility test: At room temperature, dissolve 10mg of sample in 1mL of solvent (common solvents such as NMP, DMAc, Py, etc.) and observe the dissolution of the sample. If it is not completely dissolved, heat to 60℃ and continue to observe and record the dissolution.

[0040] (5) Molecular weight determination (GPC): The sample was prepared into a solution of 3-5 mg / mL and measured using a DAWN HELEOS II multi-angle laser light scattering instrument. The mobile phase was THF, and the flow rate was 0.5 mL / min. The weight-average molecular weight (Mw) of the polymer was obtained. w Number Mean M n And the dispersion index PDI.

[0041] (6) Thermogravimetric analysis (TGA): Thermogravimetric analysis was performed using TG-DTA under N2 atmosphere, with the temperature increased at 10℃ / min, and the thermogravimetric analysis of the sample was performed in the range of 20 to 800℃.

[0042] (7) Dynamic thermomechanical analysis (DMA) test: The heat resistance of the polymer was characterized by DMA. The film was cut into fiber strips of 5cm×5mm size, fixed on a fixture, and the heating rate was set to 10℃ / min. The temperature was increased from room temperature to 420℃ at 1Hz.

[0043] (8) Optical performance test (UV-Vis): The polymer film was cut into 20mm×45mm pieces and tested using a U-3310 UV-Vis spectrometer with a wavelength of 200~800nm.

[0044] (9) Mechanical property test: The polymer film was cut into 2mm×50mm pieces and tensile test was performed using a CMT8012 universal electronic testing machine. The tensile speed was set to 5mm / min and repeated 3 times. The average value was taken.

[0045] (10) Water absorption rate test (W) U First, dry the polymer film in a 100℃ oven. Then, cut the dried film into 10mm × 10mm pieces and weigh M. dry Soak in deionized water for 24 hours, wipe off the moisture on the film surface, and weigh M. wet Calculate the water absorption rate W U .

[0046] W U Calculation formula: W U =(M wet –M dry )×100% / M dry Among them, M dry Mass at drying time / g, M wet : Mass after water absorption / g.

[0047] (11) Water contact angle test: The hydrophobicity of the polymer was tested using a contact angle meter (OCA15EC type). The test liquid was distilled water. The film was cut into 8mm×8mm sizes and attached to the double-sided adhesive of a glass slide. The test was conducted at room temperature.

[0048] (12) Dielectric property test (DC): The test was conducted using an E4980A precision impedance analyzer. The PA film was cut into 15mm×15mm pieces, and the conductive adhesive was cut into 8mm pieces. The conductive adhesive was then attached to both sides of the film and placed on the test fixture for testing at room temperature. The test frequency was 0.1KHz~100KHz.

[0049] Example 1

[0050] The synthetic route for 3-(4-aminophenoxy)-9-(4-amino-2-trifluoromethylphenyl)carbazole (APATPC) is as follows:

[0051]

[0052] (1) Synthesis of 2-chloro-5-nitrotrifluorotoluene (CNTB):

[0053] In a 500 mL round-bottom flask, 121 g (0.67 mol) of o-chlorotrifluorotoluene and 112 mL of concentrated sulfuric acid were added sequentially. The flask was placed in an ice bath and stirred. A mixed solution of H₂SO₄ / HNO₃ (V:V = 1:1, 225 mL) was slowly added dropwise. The ice was removed, and the reaction was allowed to proceed at room temperature for 8 h. After the reaction was complete, the mixture was slowly poured into an ice / water mixture. The lower oily layer was extracted with distilled water until neutral, dried over anhydrous MgSO₄, and filtered. The resulting product was CNTB, with a yield of 93%.

[0054] 1 H NMR (400MHz, CDCl3): δ=8.58 (d, J=2.3Hz, 1H), 8.36 (dd, J=8.7, 2.3Hz, 1H), 7.73 (d, J=8.8Hz, 1H).

[0055] (2) Synthesis of N-(4-nitro-2-trifluoromethylphenyl)carbazole (NTPC):

[0056] Carbazole (16.72 g, 0.10 mol), K₂CO₃ (13.80 g, 0.10 mol), and DMF (200 mL) were added sequentially to a 500 mL three-necked flask. Under N₂ conditions, 2-chloro-5-nitrotrifluorotoluene (CNTB) (24.81 g, 0.11 mol) was injected using a syringe. The mixture was heated to 150 °C and refluxed for 24 h. After cooling to room temperature, the precipitate was slowly added dropwise to ice water. The precipitate was then collected by rotary evaporation onto a column and eluted with pure PE to obtain a yellow powder. Recrystallization from anhydrous ethanol yielded yellow crystals, which were NTPC, in 86.8% yield. The melting point is 74–76 °C.

[0057] 1 H NMR (400MHz, CDCl3): δ = 8.86 (s, 1H), 8.62 (d, J = 10.9Hz, 1H), 8.15 (d, J = 7.7Hz, 2H), 7.6 1(d,J=8.6Hz,1H), 7.40(t,J=7.6Hz,2H), 7.33(t,J=7.5Hz,2H), 6.93(d,J=8.1Hz,2H).

[0058] (3) Synthesis of 3-acetyl-9-(4-nitro-2-trifluoromethylphenyl)carbazole (ANTPC):

[0059] AlCl3 (1.60 g, 15 mmol), dichloromethane (DCM) (20 mL), and AcCl (1.96 g, 25 mmol) were added sequentially to a 50 mL round-bottom flask placed in an ice bath and activated for 10 min. The activated solution was then slowly added dropwise through a constant-pressure funnel to a solution of N-(4-nitro-2-trifluoromethylphenyl)carbazole (3.56 g, 10 mmol) and DCM (30 mL) in an ice bath for 30 min. The ice bath was then removed, and the reaction was allowed to proceed at room temperature for 3 h. After the reaction was complete, HCl:H2O (10 mL:25 mL) was added to quench the reaction for 10 min, and the solution color changed from dark green to yellow. Extraction was performed with DCM, and the solution was loaded onto a column with a PE:EA ratio of 5:1 to obtain a yellow powder with a yield of 60%. The melting point was 156.4–158.3 °C.

[0060] 1 H NMR (400MHz, CDCl3): δ=8.88(s,1H), 8.79(s,1H), 8.66(d,J=10.8Hz,1H), 8.21(d,J=7.6Hz,1H), 8.05(d ,J=8.6Hz,1H), 7.65(d,J=8.6Hz,1H), 7.42(dt,J=22.0,7.3Hz,2H), 6.95(d,J=8.3Hz,2H), 2.73(s,3H).

[0061] IR(KBr):υ max =3054cm -1 (Stretching vibration of -CH3); 1673cm -1 (Stretching vibration of C=O); 1589cm -1 (Stretching vibration of CN bonds on carbazole); 1349 and 1533 cm -1 (Symmetric and antisymmetric stretching vibrations of -NO2); 1307 cm -1 (Stretching vibration of CF); 732cm -1 (Bending vibration peak of Ar-H).

[0062] (4) Synthesis of 3-acetoxy-9-(4-nitro-2-trifluoromethylphenyl)carbazole (AONTPC):

[0063] 3-Acetyl-9-(4-nitro-2-trifluoromethylphenyl)carbazole (1.99 g, 5 mmol), m-chloroperoxybenzoic acid (m-CPBA) (1.55 g, 9 mmol), and 10 mL of DCM were sequentially added to a 50 mL round-bottom flask and stirred at room temperature for 5 h. The mixture was then filtered. The filtrate was rotary evaporated, and the solution was loaded onto a column at a PE:EA ratio of 10:1 to obtain a yellow powder with a yield of 92%. The melting point was 113.9–115.1 °C.

[0064] 1 H NMR (400MHz, CDCl3): δ=8.86(d,J=2.6Hz,1H), 8.62(dd,J=8.6,2.6Hz,1H), 8.07(d,J=7.0Hz,1H), 7.85(d,J=2.3Hz,1H), 7.59(d,J=9.0H z,1H), 7.43–7.37(m,1H), 7.32(t,J=7.0Hz,1H), 7.11(dd,J=8.7,2.3Hz,1H), 6.92(d,J=3.6Hz,1H), 6.89(d,J=4.2Hz,1H), 2.37(s,3H).

[0065] IR(KBr):υ max =3087,1754cm -1 (Stretching vibration of carbonyl C=O in ester group), 1589, 1537, 1349, 1307, 1213 cm⁻¹ -1 (Stretching vibration of CO in the alkoxy group of the ester group), 747 cm⁻¹ -1 .

[0066] (5) Synthesis of 3-hydroxy-9-(4-nitro-2-trifluoromethylphenyl)carbazole (HNTPC):

[0067] 0.4143 g (10 mmol) of 3-acetoxy-9-(4-nitro-2-trifluoromethylphenyl)carbazole, 10% NaOH solution, and 10 mL of EtOH were placed in a 50 mL round-bottom flask and refluxed at 85 °C with stirring for 2 h. The resulting solution was slowly added dropwise to ice water, and the pH was adjusted to neutral with 10% HCl. The mixture was filtered to obtain an orange powder. The yield was 98%. The melting point was 127.9–128.5 °C.

[0068] 1H NMR (400MHz, CDCl3): δ = 8.85 (s, 1H), 8.69–8.52 (m, 1H), 8.04 (s, 1H), 7.62 (s, 1H), 7.57–7.52 (m, 1H) ), 7.42–7.33(m,1H), 7.29(d,J=7.1Hz,1H), 7.01–6.85(m,2H), 6.79(d,J=8.7Hz,1H), 4.92(s,1H).

[0069] IR(KBr):υ max =3511 and 3464cm -1 (Characteristic absorption peaks of phenolic hydroxyl group Ar-OH), 1584, 1535, 1349, 1307, 742 cm⁻¹ -1 .

[0070] (6) Synthesis of 3-(4-nitrophenoxy)-9-(4-nitro-2-(trifluoromethylphenyl)carbazole (NPNTPC):

[0071] 3-hydroxy-9-(4-nitro-2-trifluoromethylphenyl)carbazole (3.7230 g, 10 mmol), p-fluoronitrobenzene (1.4102 g, 10 mmol), CsF (2.7360 g, 18 mmol), and DMSO (20 mL) were added to a 50 mL round-bottom flask and stirred under reflux at 110 °C for 0.75 h. After the reaction was complete, the cooled solution was slowly added dropwise to ice water and filtered to obtain a yellow powder with a yield of 94%. The melting point was 202.2–203.3 °C.

[0072] 1 H NMR (600MHz, CDCl3): δ=8.88(d,J=2.6Hz,1H),8.65(dd,J=8.6,2.6Hz,1H),8.21(d,J=9.3Hz,2H),8.07(d,J=7.8Hz,1H),7.86(d,J=2.3Hz,1H),7. 65(d,J=8.5Hz,1H),7.44(t,J=7.7Hz,1H),7.34(t,J=7.5Hz,1H),7.15(dd,J=8.7,2.3Hz,1H),7.05(d,J=9.3Hz,2H),6.96(dd,J=11.6,8.5Hz,2H).

[0073] IR(KBr):υ max =1589;1514;1340;1305;1224cm -1 (Stretching vibration of the ether bond Ar-O-Ar); 747cm -1 .

[0074] (7) Synthesis of 3-(4-aminophenoxy)-9-(4-amino-2-trifluoromethylphenyl)carbazole (APATPC):

[0075] 3-(4-nitrophenoxy)-9-(4-nitro-2-(trifluoromethylphenyl)carbazole (4.93 g, 10 mmol), 0.12 g of Pd / C, and 30 mL of ethanol were added sequentially to a 50 mL three-necked flask. Under N2 protection, 15 mL of hydrazine hydrate was slowly injected, and the mixture was heated to 80 °C and reacted for 24 h. After the reaction was completed, Pd / C was removed by hot filtration. After the reaction solution cooled, it was extracted with DCM, and the lower layer was rotary evaporated. The solution was then loaded onto a column with a PE:EA ratio of 2:1 to give a pale yellow solid with a yield of 76%. The melting point was 105.0–107.7 °C.

[0076] 1 H NMR (400MHz, CDCl3): δ = 8.10 (d, J = 7.7Hz, 1H), 7.70 (d, J = 2.4Hz, 1H), 7.34 (t, J = 7.7Hz, 1H), 7.18 (d, J = 7.5Hz, 1H), 7.15 (d, J = 2.4Hz, 1H), 7.07 (d ,J=8.5Hz,1H),6.97(ddd,J=16.7,8.7,2.5Hz,2H),6.89(t,J=8.1Hz,2H) ,6.77(d,J=8.8Hz,2H),6.58(d,J=8.8Hz,2H),6.02(s,2H),4.88(s,2H).

[0077] IR(KBr):υ max =3487 and 3393cm -1 (Symmetric and asymmetric stretching vibrations of -NH2); 1584; 1334; 1260; 747 cm -1 .

[0078] Example 2

[0079] The preparation routes for fluorinated carbazole-containing polyetherimides PI-1 to PI-5 are as follows:

[0080]

[0081] Chemical imidization method: Taking polymer PI-5 as an example, a 50 mL three-necked flask was placed in an ice-water bath under N2 protection. 0.8660 g (2 mmol) of 3-(4-aminophenoxy)-9-(4-amino-2-trifluoromethylphenyl)carbazole (APATPC) and 2 mL of DMAc were added to the flask. After stirring until the solid was completely dissolved, 0.8885 g (2 mmol) of 6FDA was added in batches, and an appropriate amount of DMAc was added to adjust the solid-liquid ratio to approximately 20%. After incubating on ice for 1 hour, the ice was removed, and the reaction was allowed to proceed at room temperature for 12 hours to obtain a viscous PAA solution. This solution was appropriately diluted, and a mixed solution of 2 mL Ac2O and 2 mL Py was added and stirred until homogeneous. After reacting at 110 °C for 5 hours, the solution was slowly added dropwise to 100 mL of methanol, resulting in the precipitation of pale yellow fibers. Extraction with methanol in a Soxhlet extractor for 24 hours was performed, and the product was dried to obtain the target polymer PI-5.

[0082] PI-1: 1 H NMR (600MHz, DMSO-d6): δ = 11.02 (s, 1H), 10.41 (d, J = 17.5Hz, 1H), 8.63 (s, 1H), 8 .50–7.51(m,10H),7.42(s,1H),7.20(d,J=46.4Hz,2H),7.01(d,J=24.3Hz,4H).

[0083] PI-2: 1 H NMR (600MHz, DMSO-d6): δ = 8.57 (d, J = 19.3Hz, 1H), 8.49 (s, 1H), 8.46–8.32 (m, 3H), 8.30 (s, 1H), 8.22 (s ,1H),8.11(d,J=25.6Hz,3H),7.89(s,1H),7.47(s,3H),7.27(d,J=36.4Hz,2H),7.10(d,J=65.5Hz,4H).

[0084] PI-3: 1 H NMR (600MHz, DMSO-d6): δ = 8.37–8.06 (m, 10H), 7.85 (s, 1H), 7.45 (s, 3H), 7.25 (d, J = 39.5Hz, 2H), 7.18–7.06 (m, 3H), 7.02 (d, J = 4.9Hz, 1H).

[0085] PI-4: 1H NMR (600MHz, DMSO-d6): δ = 8.28 (d, J = 16.2Hz, 2H), 8.18 (d, J = 6.9Hz, 1H), 8.13–8.02 (m, 3H), 7.81 (s, 1H), 7.7 7–7.57(m,4H),7.41(d,J=5.8Hz,3H),7.24(d,J=41.8Hz,2H),7.10(d,J=26.0Hz,3H),7.01(d,J=7.9Hz,1H).

[0086] PI-5: 1 H NMR (600MHz, DMSO-d6): δ=8.33–8.02(m,6H),7.95(s,2H),7.83(d,J=14.1Hz,2H),7.7 3(s,1H),7.41(d,J=8.2Hz,3H),7.25(d,J=61.0Hz,2H),7.06(dd,J=59.4,7.6Hz,4H).

[0087] Example 3

[0088] Preparation of fluorinated carbazole-containing polyetherimide films:

[0089] Taking PI-5 as an example, the PI-5 sample (0.1-0.12 g) was dissolved in DMAc (3 mL), filtered with a nanofiltration membrane, and left to stand in a refrigerator until the bubbles completely disappeared. Using the flow-delay method, it was evenly dropped onto a preheated glass plate, dried at 80°C for 2 h, then heated to 120°C and dried for another 2 h. After cooling to room temperature, it was peeled off to obtain the dried polyetheramide film PI-5.

[0090] Performance testing and characterization:

[0091] (1) Infrared spectrum of fluorinated carbazole-containing polyetherimide:

[0092] The FT-IR spectra of this series of polyetherimides are as follows: Figure 1 As shown, at 3200cm -1 and 1520cm -1 No characteristic absorption peak of the amide bond was observed at 1778 cm⁻¹, and the symmetric and asymmetric stretching vibrations of the C=O bond on the imide ring appeared at 1778 cm⁻¹, respectively. -1 and 1725cm -1 Location; 1599cm -1 The absorption peak at that point corresponds to the stretching vibration of the CN bond in the imide ring; the other absorption peaks also correspond to the characteristic peaks of functional groups such as -NO2, -CF3 and ether bond (Ar-O-Ar).

[0093] (2) Molecular weight of fluorinated carbazole-containing polyetherimide:

[0094] Table 1 shows the molecular weight (GPC) of this series of PEIs. As can be seen from Table 1, the GPC values ​​of all polymers in this series exceed 50,000, indicating a high molecular weight. This characteristic suggests that this series of PEIs possesses good film-forming properties.

[0095] Table 1. Molecular weight of polyetherimides PI-1 to PI-5

[0096]

[0097]

[0098] a M w Weight-average molecular weight; b M n Number-average molecular weight; c PDI: Dispersion Index (M w / M n ).

[0099] (3) Solubility properties of fluorinated carbazole-containing polyetherimide:

[0100] Table 2 details the solubility of this series of PEIs in various common solvents. As shown in Table 2, this series of PEIs generally exhibits good solubility characteristics. This is attributed to the abundance of ether bonds and flexible trifluoromethyl groups in the PEI molecules. These structures not only weaken the conjugation effect of aromatic rings and reduce the rigidity of the molecular chains, but also reduce the close packing between molecular chains, effectively hindering the formation of CTCs. This allows PEIs to dissolve in most nonpolar solvents (such as DMAc, NMP, and Py) at room temperature. However, PI-2, due to its rigid biphenyl structure, exhibits the worst solubility compared to other PEIs in the series. The remaining PEIs are all soluble in THF, while PI-3 only shows slight solubility in THF after heating to 60℃.

[0101] Table 2. Solubility of polyetherimides PI-1 to PI-5 in different solvents

[0102]

[0103] +++ Soluble at room temperature; ++– Completely soluble at 60℃; +–– Slightly soluble on heating; ––– Insoluble on heating.

[0104] (4) Optical properties of fluorinated carbazole-containing polyetherimide:

[0105] Table 3. Light transmittance properties of polyetherimides PI-1 to PI-5

[0106]

[0107] T(%): transmittance at 500nm, 600nm, 700nm, and 800nm; λ0: cutoff wavelength.

[0108] The UV-Vis curves of this series of PEIs films are as follows: Figure 2 As shown in Table 3, the specific data are as follows. Table 3 shows that the cutoff wavelength of this series of PEIs films is 362–385 nm, indicating that PEIs have good optical transmittance. This characteristic is mainly attributed to the large-volume carbazole groups and trifluoromethyl groups introduced into the PEIs main chain, which greatly disrupts the ordered arrangement of the molecular chain, effectively hindering the formation of CTC, thereby improving the optical transparency of the PEIs films.

[0109] Among them, PI-5 has the shortest cutoff wavelength (362 nm) and exhibits the best optical transparency in the series, with a transmittance of up to 83.0% at 500 nm. This is attributed to the bis-CF3 group in the 6FDA structure, which effectively inhibits the formation of CTC and significantly enhances the optical transparency of PEIs. Furthermore, PI-4, due to its abundant ether bonds, reduces the packing density of the molecular chains, thus also exhibiting good optical transparency. In contrast, PI-1 and PI-2 are rich in rigid pyromellitic / biphenyl structures. These structures enhance the conjugation effect and rigidity of the molecular chains, promoting intermolecular interactions. Consequently, PI-1 and PI-2 show relatively poor transparency, with transmittances of only 50.6% and 60.5% respectively at 500 nm.

[0110] (5) Thermal properties of fluorinated carbazole-containing polyetherimide:

[0111] The thermal properties of this series of polyetherimides are detailed in Table 4, and the TGA curves are shown in [Table 4]. Figure 3 In (a), the DMA curve is shown in Figure 1. Figure 3 (b) As shown in Table 5.5, this series of PEIs exhibits excellent thermal stability, with its T... g The temperature ranges from 273.5 to 341.9℃, T 5％ All above 405.5℃, T max All have a residual mass ratio of no less than 540℃ and 800℃, which is generally greater than 54.8%. This excellent performance is mainly attributed to the fact that the carbazole group increases the free volume of the molecular chain while restricting the movement of the molecular chain, which makes the series of PEIs have excellent heat resistance.

[0112] Table 4. Thermal properties of polyetherimides PI-1 to PI-5

[0113]

[0114] a T g Glass transition temperature; b T 5％ 5% thermal weight loss temperature; c T 10％ 10% thermal weight loss temperature; d R w Residual rate at 800℃; e T max Maximum thermal weight loss temperature.

[0115] From 3(b), we know that T of PI-1 g The highest temperature reached 341.9℃, mainly due to the presence of rigid homophenyl units in its structure. These rigid structures significantly enhance the close packing of the molecular chains, thereby improving its thermal properties. PI-2 is rich in biphenyl structures, which increases the compactness of PI, resulting in a relatively high energy required for its glass transition. In contrast, the main chain of PI-4 contains a large number of ether bonds, promoting chain segment movement, leading to a lower thermal decomposition temperature, reduced residual mass, and a lower Tg. g (273.5℃) is the lowest in the series.

[0116] (6) Mechanical properties of fluorinated carbazole-containing polyetherimides:

[0117] Figure 4 The mechanical property curves of this series of PEIs are shown in Table 5. As can be seen from Table 5, the tensile strength of this series of PEIs films ranges from 135.44 to 169.65 MPa, and the highest elastic modulus reaches 3.00 GPa, indicating excellent mechanical properties. Among them, the rigid structure of pyromellitic phenylene affects the flexibility of the molecular chain, resulting in the lowest tensile strength (135.44 MPa) for PI-1. PI-4, rich in ether bonds, exhibits better tensile strength and elongation at break. Due to the presence of multiple trifluoromethyl groups in the 6FDA monomer, PI-5 exhibits the best tensile strength in the series, reaching as high as 169.65 MPa. In summary, this series of PEIs films demonstrates excellent mechanical properties.

[0118] Table 5. Mechanical properties of polyetherimides PI-1 to PI-5

[0119]

[0120] a T s Tensile strength; b T m : Elastic modulus; c E b Elongation at break.

[0121] (7) Water absorption rate and water contact angle of fluorinated carbazole-containing polyetherimide

[0122] Table 6 details the water absorption rate and water contact angle of this series of PEIs. The water absorption rate ranges from 0.23% to 1.01%, and the contact angle ranges from 89.6° to 95.2°. Among them, PI-5 exhibits the lowest water absorption rate because its main chain is rich in hydrophobic groups -CF3, which effectively weakens the interaction with water molecules. PI-4 has the highest water absorption rate, accompanied by a lower contact angle. This is attributed to the fact that the ether bonds in its structure easily form hydrogen bonds with water molecules, leading to an increased water absorption capacity. In addition, PI-2 shows a slightly higher water absorption rate than PI-1. This may be because the presence of the biphenyl structure induces the twisting of the molecular chain, thereby slightly increasing the contact area with water molecules, resulting in PI-2 having a stronger water absorption capacity than PI-1.

[0123] Table 6. Water absorption rate and contact angle of polyetherimides PI-1 to PI-5

[0124]

[0125] (8) Dielectric properties of fluorinated carbazole-containing polyetherimide

[0126] Table 7 details the dielectric properties of this series of PEIs. As shown in Table 7, the dielectric constant of these PEIs ranges from 1.23 to 1.86 at 1 kHz, exhibiting excellent dielectric characteristics. This phenomenon is mainly attributed to the introduction of carbazole and trifluoromethyl groups in the main chain, which increases the inter-chain spacing and free volume ratio, thereby effectively reducing the polymer's dielectric constant. PI-5, in particular, shows a dielectric constant as low as 1.23 at 1 kHz. This is primarily because the 6FDA unit is rich in trifluoromethyl structures; the CF bond, due to its low polarizability and high bond energy, significantly reduces the material's electronic polarization and promotes the expansion of free volume. Furthermore, the -CF3 group also reduces the water absorption rate of PEIs, an effect that further contributes to the reduction of the material's dielectric constant. In summary, this series of PEIs materials exhibits excellent dielectric properties.

[0127] Table 7. Dielectric properties of polyetherimides PI-1 to PI-5

[0128]

Claims

1. A fluorinated carbazole-containing polyetherimide, characterized in that: It has the following repeating structural units: ； in, Ar for , , , or ,in, Indicates a connection key.

2. The fluorinated carbazole-containing polyetherimide according to claim 1, characterized in that: Number-average molecular weight is 4 × 10 4 ~6×10 4 .

3. The method for preparing a fluorinated carbazole-containing polyetherimide according to claim 1 or 2, characterized in that: Includes the following steps: 1) The diamine monomer and the dianhydride monomer are subjected to a polycondensation reaction to obtain a polyamic acid intermediate; 2) The polyamic acid intermediate is chemically imidized under the promoting action of acetic anhydride and pyridine to obtain fluorinated carbazole-containing polyetherimide; The diamine monomer has the following molecular structure: ； The dianhydride monomer has the following molecular structure: ； Where Ar is , , , or ,in, Indicates a connection key.

4. The method for preparing a fluorinated carbazole-containing polyetherimide according to claim 3, characterized in that: The conditions for the polycondensation reaction are as follows: first, react at a temperature of -5°C to 5°C for 0.5 to 1.5 hours, and then react with stirring at room temperature for 12 to 14 hours.

5. A method for preparing a fluorinated carbazole-containing polyetherimide according to claim 3 or 4, characterized in that: The polycondensation reaction is carried out in anhydrous... N,N The process is carried out in dimethylacetamide (DMAc).

6. The method for preparing a fluorinated carbazole-containing polyetherimide according to claim 5, characterized in that: The amount of anhydrous DMAc used is such that the solid content of the polymerization system is maintained at 15-25%.

7. The method for preparing a fluorinated carbazole-containing polyetherimide according to claim 3, characterized in that: The conditions for chemical imidization are as follows: first, add acetic anhydride and pyridine and stir evenly at room temperature, then raise the temperature to 105~115°C and stir for 4~6 hours.

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