Benzocyclobutene-containing aromatic diamine, benzocyclobutene-containing aromatic polyamide and preparation method thereof

Abstract

The invention provides benzocyclobutene-containing aromatic diamine and a preparation method thereof, and the preparation method comprises the following steps: dissolving 3-[1, 4-benzenediol]-bicyclo [4.2. 0]-octyl-1, 3, 5-triene and 4-nitrochlorobenzene in a first organic solvent, and reacting under an alkaline condition to obtain a benzocyclobutene-containing dinitro compound; and dissolving the benzocyclobutene-containing dinitro compound in a second organic solvent, and reducing in a hydrogen atmosphere to obtain the benzocyclobutene-containing aromatic diamine compound. The invention also provides a benzocyclobutene-containing aromatic polyamide polymer and a preparation method thereof. According to the linear aromatic polyamide and the cross-linked aromatic polyamide prepared by the invention, the content of benzocyclobutene in the structure can be adjusted according to a use scene, so that the mechanical strength, the thermal stability and the CTE are changed to adapt to different application requirements, and the linear aromatic polyamide is relatively good in solubility in an organic solvent, so that the linear aromatic polyamide is easy to process and relatively good in film-forming property.

Description

Technical Field

[0001] The invention relates to the technical field of polyaromatic amides, and in particular to aromatic diamines containing benzocyclobutene, polyaromatic amides and preparation methods. Background Art

[0002] Polyaramid refers to a high-performance polymer with at least 85% amide groups directly connected to two aromatic rings in the main chain. According to the different connection positions of the amide groups to the benzene rings, polyaramid can be divided into para-polyaramid, meta-polyaramid, ortho-polyaramid, etc. The characteristics of this polymer include high melting point, high modulus, high strength and radiation resistance, etc., and it is widely used in the production of high-performance synthetic fibers. In my country, polyaramid fiber is also called aramid. Its most notable characteristics include light weight, flame retardancy, temperature resistance, insulation, radiation resistance, high strength, high elastic modulus, etc.; it is widely used in military defense, security protection, aerospace, environmental protection, electronic and electrical materials and other fields.

[0003] A large number of polar amide groups (-CO-NH-) are repeated in the molecular chain segments of polyaromatic amide. The amino hydrogen on this group can combine with the carbonyl oxygen on the amide group of another molecule to form a highly directional and efficient interchain hydrogen bond network, which makes this type of material have a high crystallization tendency, high cohesive energy density, and poor solubility in organic solvents. Generally, it can only be processed after being dissolved in concentrated sulfuric acid, but concentrated sulfuric acid is very corrosive and easily corrodes processing equipment, and polymers are easily degraded in sulfuric acid. These shortcomings greatly limit the application of polyaromatic amide. In addition, different fields have different performance requirements for polyaromatic amide. The performance of existing polyaromatic amide is not expandable and flexible enough, and it is difficult to adapt to the application requirements of various fields. Summary of the invention

[0004] The purpose of the present invention is to provide an aromatic diamine containing benzocyclobutene in view of the defects of the prior art, the structure of which is:

[0005]

[0006] The method for preparing an aromatic diamine containing benzocyclobutene comprises the following steps:

[0007] Under nitrogen protection, 3-[1,4-benzenediol]-bicyclo[4.2.0]-octa-1,3,5-triene and 4-nitrochlorobenzene are dissolved in an amide organic solvent or a pyrrolidone organic solvent and reacted under alkaline conditions to obtain a dinitro compound containing benzocyclobutene;

[0008] The dinitro compound containing benzocyclobutene is dissolved in an ester organic solvent and then reduced under a hydrogen atmosphere to obtain an aromatic diamine compound containing benzocyclobutene.

[0009] Furthermore, the specific method of the reaction under alkaline conditions is: dissolving potassium carbonate or sodium carbonate in a first organic solvent to form alkaline conditions, the molar number of potassium carbonate or sodium carbonate is 2-2.5 times that of 3-[1,4-benzenediol]-bicyclo[4.2.0]-octa-1,3,5-triene, the reaction temperature is 80-130°C, and the reaction time is 5-10 hours.

[0010] Furthermore, the specific method of reducing the dinitro compound containing benzocyclobutene under a hydrogen atmosphere is: adding a Pd / C catalyst to the dinitro compound containing benzocyclobutene, wherein the amount of Pd in ​​the Pd / C catalyst is 5-10‰wt% of the dinitro compound containing benzocyclobutene;

[0011] The molar ratio of the 3-[1,4-benzenediol]-bicyclo[4.2.0]-octa-1,3,5-triene to 4-nitrochlorobenzene is 1:2.0-2.3.

[0012] A linear polyaromatic amide, having the following structure:

[0013]

[0014] x is 1-50, y is 0-49;

[0015] A cross-linked polyaramid having the following structure:

[0016]

[0017] x is 1-50, y is 0-49.

[0018] The preparation method of linear polyaromatic amide comprises the following steps:

[0019] Aromatic diamine containing benzocyclobutene, terephthalic acid, 3,4'-ODA and CaCl2 or LiCl are added into a reaction container, and after nitrogen substitution, P(OPh)3, pyridine and NMP are added for reflux reaction to obtain linear polyaromatic amide.

[0020] The preparation method of cross-linked polyaramid comprises the following steps:

[0021] Aromatic diamine containing benzocyclobutene, terephthalic acid, 3,4'-ODA and CaCl2 or LiCl are added into a reaction container, and after nitrogen substitution, P(OPh)3, pyridine and NMP are added for reflux reaction to obtain linear polyaromatic amide;

[0022] Under inert gas conditions, the linear polyaromatic amide is thermally cured and then annealed to obtain a cross-linked polyaromatic amide containing a tetrahydrodibenzocyclooctadiene structure.

[0023] Furthermore, the reflux reaction conditions are 100-150° C. for 12-24 hours; the molar ratio of the total amount of the aromatic diamine containing benzocyclobutene and 3,4'-ODA, terephthalic acid, CaCl2, P(OPh)3, and pyridine is 1:1:(2-5):(4-8):(6-12).

[0024] Furthermore, the specific method of annealing the linear polyaromatic amide after heat curing is: heating the linear polyaromatic amide to 270° C. for heat curing for 6-10 hours, and annealing at 300° C. for 12-20 hours.

[0025] The beneficial effects of the present invention are:

[0026] 1. Introducing flexible segments such as ether bonds or side groups that destroy the regularity of the molecular chain into the molecular structure of rigid polyaromatic amide to prepare linear polyaromatic amide with good solubility. This solves the problem of poor solubility of such materials in organic solvents.

[0027] 2. The linear polyaromatic amide and cross-linked polyaromatic amide prepared by the present invention have excellent mechanical strength and thermal stability. After the linear polyaromatic amide is cross-linked, a cross-linked network of tetrahydrodibenzocyclooctadiene (DBCOD) structure is formed between the molecular chains, which improves the thermal stability of the polymer. d 5％ The average rise is 36°C, T d 10％ The average increase is 30°C. The ring opening of benzocyclobutene forms a cross-linked network, which enhances the modulus and hardness.

[0028] 3. The linear polyaromatic amide and cross-linked polyaromatic amide prepared by the present invention can adjust the content of benzocyclobutene in the structure according to the usage scenario, so that the mechanical strength, thermal stability and CTE are changed to adapt to different application requirements.

[0029] 4. The cross-linked polyaromatic film prepared by the present invention has good film-forming properties, and the cross-linked polyaromatic film prepared has good flexibility and transparency, and shows high processability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of Example 4.

[0031] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of Example 5-8.

[0032] Figure 3 This is the TGA curve of the linear, cross-linked polyaramid in Example 6.

[0033] Figure 4 The DSC curve of linear polyaromatic amide in Examples 4-8.

[0034] Figure 5 This is the DSC curve of the linear, cross-linked polyaramid in Example 4.

[0035] Figure 6 4-8 is the XRD curve of the cross-linked polyaromatic amide.

[0036] Figure 7 This is the linear, cross-linked polyaramid nanoindentation curve of Example 7.

[0037] Figure 8 This is the TMA curve of the cross-linked polyaromatic amide in Examples 4-8.

[0038] Fig. 9 This is the cross-linked polyaramid film sample in Example 4-8. DETAILED DESCRIPTION

[0039] The drugs used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods in the art unless otherwise specified.

[0040] The present invention is further illustrated by the following examples and comparative examples.

[0041] Example 1

[0042] An aromatic diamine containing benzocyclobutene, namely 3-[2,5-bis-(4-aminophenoxy)-phenyl]-bicyclo[4.2.0]-octa-1,3,5-triene, has the structure:

[0043]

[0044] Example 2

[0045] The method for preparing the aromatic diamine containing benzocyclobutene in Example 1 comprises the following steps:

[0046] Step (1): Preparation of 3-[2,5-bis-(4-nitrophenoxy)-phenyl]-bicyclo[4.2.0]-oct-1,3,5-triene: Weigh 3-[1,4-benzenediol]-bicyclo[4.2.0]-oct-1,3,5-triene (2.122 g, 10 mmol), 4-nitrochlorobenzene (3.307 g, 21 mmol), anhydrous K2CO3 (3.040 g, 22 mmol) and add them to a 250 mL single-necked flask, and then add 30 mL of DMF. Place under nitrogen, heat to 120° C., and react for 8 hours. After the reaction is completed, add 100 mL of deionized water, and a black solid precipitates. The obtained aqueous phase is extracted 3 times with 30 mL of ethyl acetate, the organic phases are combined, anhydrous sodium sulfate is added for drying, filtered and concentrated, and then the compound is obtained by solvent petroleum ether-ethyl acetate column chromatography to obtain 4.15 g of the compound with a yield of 92%.

[0047] Step (2): Preparation of 3-[2,5-bis-(4-aminophenoxy)-phenyl]-bicyclo[4.2.0]-oct-1,3,5-triene: Weigh 3-[2,5-bis-(4-nitrophenoxy)-phenyl]-bicyclo[4.2.0]-oct-1,3,5-triene (4.521 g, 10 mmol), add 150 mL of ethyl acetate into a 250 mL three-necked flask, replace nitrogen, add a palladium carbon catalyst (1.36 g) with a metal content of 5% into the three-necked flask, replace hydrogen, and react for 48 hours. After the reaction is completed, replace the nitrogen atmosphere, filter the palladium carbon, and concentrate it. Then, pure 3-[2,5-bis-(4-nitrophenoxy)-phenyl]-bicyclo[4.2.0]-oct-1,3,5-triene 3.55 g can be obtained by solvent petroleum ether-ethyl acetate column chromatography, with a yield of 90%.

[0048] Finally, the aromatic diamine compound 3-[2,5-bis-(4-aminophenoxy)-phenyl]-bicyclo[4.2.0]-octa-1,3,5-triene was obtained, and its H NMR spectrum, IR spectrum, mass spectrum and melting point data are as follows:

[0049] 1 H NMR (400MHz, DMSO-d6): δ12.82(s,1H),7.98(d,J=8.1Hz,2H),7.87(d,J=8.0Hz,2H),7.28(d,J=7.6Hz,1H),7.24-7.13(m,6H), 7.06(d,J=7.6Hz,1H),6.95(d,J=8.2Hz,2H),3.09(s,4H).FT-IR:ν=3072,2928,1681,1600,1493,1467,1225,1163,935,858cm -1 .ESI-MS:394[MH] - ; HRMS: [MH] - Calculate for C 26 H 22 N2O2 - ,394.1681,found394.1765.Mp:88.5-93.1℃(ethyl acetate).

[0050] Example 3

[0051] The polyaromatic amide polymer containing benzocyclobutene prepared from aromatic diamine containing benzocyclobutene has the following structure:

[0052] The structural formula of linear polyaromatic amide containing benzocyclobutene is as follows:

[0053]

[0054] x is 1-50, y is 0-49;

[0055] The cross-linked polyaromatic amide containing tetrahydrodibenzocyclooctadiene structure has the following structural formula:

[0056]

[0057] x is 1-50, y is 0-49.

[0058] Example 4

[0059] A method for preparing a polyaromatic amide polymer containing benzocyclobutene prepared from an aromatic diamine containing benzocyclobutene in Preparation Example 3 specifically comprises the following steps:

[0060] 3-[2,5-bis-(4-aminophenoxy)-phenyl]-bicyclo[4.2.0]-octa-1,3,5-triene (394 mg, 1.0 mmol) and terephthalic acid (TPA) (166 mg, 1.0 mmol), CaCl2 (222 mg, 2.0 mmol) were added to a 25 mL Schlenk tube. After nitrogen replacement, P(OPh)3 (1.0 mL), pyridine (0.5 mL), and NMP (2 mL) were mixed and added to the Schlenk tube with a syringe. The reaction system was heated to 120°C and stirred thoroughly. After reacting for 24 hours, the reaction solution was cooled to room temperature, 50 mL of methanol was added, the polymer was precipitated, centrifuged and washed thoroughly with methanol, and vacuum dried at 40°C to obtain 513 mg of linear polyaromatic amide with a yield of 98%. The structure is as follows:

[0061]

[0062] x=20, y=0.

[0063] 1 H NMR (400MHz, DMSO-d6): δ10.4(s,1H),10.4(s,1H),8.1(t,J=6.1Hz,4H),7.8(d,J=8.0Hz,2H),7.7(d,J=8.4Hz, 2H),7.3(d,J=7.5Hz,2H),7.2(s,2H),7.1(dd,J=23.0,7.8Hz,5H),7.0(s,3H),6.9(d,J=8.2Hz,2H),3.1(s,4H).

[0064] The preparation method of cross-linked polyaromatic amide is as follows: linear polyaromatic amide is fully dissolved in NMP to prepare a 40 mg / mL polymer solution, and then dripped onto a clean substrate. After the solvent evaporates, the solution is dried at 110° C. for 10 hours, and the film is peeled off from the substrate to obtain a self-supporting film. The film is thermally cured at 270° C. for 6 hours under nitrogen, and annealed at 300° C. for 10 hours, and then cooled to obtain the cross-linked polyaromatic amide.

[0065] Example 5

[0066] A method for preparing a polyaromatic amide polymer containing benzocyclobutene prepared from an aromatic diamine containing benzocyclobutene in Preparation Example 3 specifically comprises the following steps:

[0067] 3-[2,5-bis-(4-aminophenoxy)-phenyl]-bicyclo[4.2.0]-octa-1,3,5-triene (197 mg, 0.6 mmol), 3,4'-ODA (60 mg, 0.3 mmol) and TPA (149 mg, 0.9 mmol), CaCl2 (222 mg, 2.0 mmol) were added to a 25 mL Schlenk tube. After nitrogen replacement, P(OPh)3 (1.0 mL), pyridine (0.5 mL), and NMP (2 mL) were mixed and added to the Schlenk tube with a syringe. The reaction system was heated to 120°C and stirred thoroughly. After reacting for 24 hours, the reaction solution was cooled to room temperature, 50 mL of methanol was added, the polymer was precipitated, centrifuged and washed thoroughly with methanol, and vacuum dried at 40°C to obtain 419 mg of linear polyaromatic amide with a yield of 99%. The structure is as follows:

[0068]

[0069] x=23, y=10.

[0070] 1 H NMR (400MHz, DMSO-d6): δ10.5(s,2H),10.4(s,1H),8.1(t,J=7.6Hz,6H),7.9-7.8(m,3H),7.7(d,J=7.8Hz,2H),7.6(d ,J=13.1Hz,1H),7.4-7.3(m,3H),7.2(s,2H),7.2-7.0(m,9H),6.9(d,J=8.0Hz,2H),6.8(d,J=7.4Hz,1H),3.1(s,4H).

[0071] The preparation method of cross-linked polyaromatic amide is as follows: linear polyaromatic amide is fully dissolved in NMP to prepare a 40 mg / mL polymer solution, and then dripped onto a clean substrate. After the solvent evaporates, the solution is dried at 110° C. for 10 hours, and the film is peeled off from the substrate to obtain a self-supporting film. The film is thermally cured at 270° C. for 6 hours under nitrogen, and annealed at 300° C. for 10 hours, and then cooled to obtain the cross-linked polyaromatic amide.

[0072] Example 6

[0073] A method for preparing a polyaromatic amide polymer containing benzocyclobutene prepared from an aromatic diamine containing benzocyclobutene in Preparation Example 3 specifically comprises the following steps:

[0074] 3-[2,5-bis-(4-aminophenoxy)-phenyl]-bicyclo[4.2.0]-octa-1,3,5-triene (197 mg, 0.5 mmol), 3,4'-ODA (100 mg, 0.5 mmol) and TPA (166 mg, 1.0 mmol), CaCl2 (222 mg, 2.0 mmol) were added to a 25 mL Schlenk tube. After nitrogen replacement, P(OPh)3 (1.0 mL), pyridine (0.5 mL), and NMP (2 mL) were mixed and added to the Schlenk tube with a syringe. The reaction system was heated to 120°C and stirred thoroughly. After reacting for 24 hours, the reaction solution was cooled to room temperature, 50 mL of methanol was added, the polymer was precipitated, centrifuged and washed thoroughly with methanol, and vacuum dried at 40°C to obtain 383 mg of linear polyaromatic amide with a yield of 98%. The structure is as follows:

[0075]

[0076] x=25, y=25.

[0077] 1 H NMR (400MHz, DMSO-d6): δ10.5(s,3H),10.4(s,1H),8.1(t,J=9.0Hz,8H),7.8(s,4H),7.7(d,J=7.9Hz,2H),7.6(d,J =10.9Hz,2H),7.4-7.3(m,3H),7.2(s,2H),7.2-7.0(m,10H),6.9(d,J=7.8Hz,4H),6.8(d,J=7.4Hz,1H),3.1(s,4H).

[0078] The preparation method of cross-linked polyaromatic amide is as follows: linear polyaromatic amide is fully dissolved in NMP to prepare a 40 mg / mL polymer solution, and then dripped onto a clean substrate. After the solvent evaporates, the solution is dried at 110° C. for 10 hours, and the film is peeled off from the substrate to obtain a self-supporting film. The film is thermally cured at 270° C. for 6 hours under nitrogen, and annealed at 300° C. for 10 hours, and then cooled to obtain the cross-linked polyaromatic amide.

[0079] Example 7

[0080] A method for preparing a polyaromatic amide polymer containing benzocyclobutene prepared from an aromatic diamine containing benzocyclobutene in Preparation Example 3 specifically comprises the following steps:

[0081] 3-[2,5-bis-(4-aminophenoxy)-phenyl]-bicyclo[4.2.0]-octa-1,3,5-triene (118 mg, 0.3 mmol), 3,4'-ODA (120 mg, 0.6 mmol) and TPA (149 mg, 0.9 mmol), CaCl2 (222 mg, 2.0 mmol) were added to a 25 mL Schlenk tube. After nitrogen replacement, P(OPh)3 (1.0 mL), pyridine (0.5 mL), and NMP (2 mL) were mixed and added to the Schlenk tube with a syringe. The reaction system was heated to 120°C and stirred thoroughly. After reacting for 24 hours, the reaction solution was cooled to room temperature, 50 mL of methanol was added, the polymer was precipitated, centrifuged and washed thoroughly with methanol, and vacuum dried at 40°C to obtain 341 mg of linear polyaromatic amide with a yield of 95%. The structure is as follows:

[0082]

[0083] x=11, y=18.

[0084] 1 H NMR (400MHz, DMSO-d6): δ10.5(s,2H),10.4(s,1H),8.1(t,J=10.4Hz,6H),7.8(s,3H),7.7(d,J=6.4Hz,1H),7.6(d,J=8.9Hz,2 H),7.5-7.3(m,2H),7.2(s,1H),7.1(q,J=10.6,7.8Hz,4H),7.0(s,2H),6.9(d,J=8.0Hz,1H),6.8(d,J=7.1Hz,1H),3.1(s,2H).

[0085] The preparation method of cross-linked polyaromatic amide is as follows: linear polyaromatic amide is fully dissolved in NMP to prepare a 40 mg / mL polymer solution, and then dripped onto a clean substrate. After the solvent evaporates, the solution is dried at 110° C. for 10 hours, and the film is peeled off from the substrate to obtain a self-supporting film. The film is thermally cured at 270° C. for 6 hours under nitrogen, and annealed at 300° C. for 10 hours, and then cooled to obtain the cross-linked polyaromatic amide.

[0086] Example 8

[0087] A method for preparing a polyaromatic amide polymer containing benzocyclobutene prepared from an aromatic diamine containing benzocyclobutene in Preparation Example 3 specifically comprises the following steps:

[0088] 3-[2,5-bis-(4-aminophenoxy)-phenyl]-bicyclo[4.2.0]-octa-1,3,5-triene (39 mg, 0.1 mmol), 3,4'-ODA (180 mg, 0.9 mmol) and TPA (166 mg, 1.0 mmol), CaCl2 (222 mg, 2.0 mmol) were added to a 25 mL Schlenk tube. After nitrogen replacement, P(OPh)3 (1.0 mL), pyridine (0.5 mL), and NMP (2 mL) were mixed and added to the Schlenk tube with a syringe. The reaction system was heated to 120°C and stirred thoroughly. After reacting for 24 hours, the reaction solution was cooled to room temperature, 50 mL of methanol was added, the polymer was precipitated, centrifuged and washed thoroughly with methanol, and vacuum dried at 40°C to obtain 317 mg of linear polyaromatic amide with a yield of 96%. The structure is as follows:

[0089]

[0090] x=6, y=40.

[0091] 1 H NMR (400MHz, DMSO-d6): δ10.5(s,2H),10.4(s,0.1H),8.1(t,J=11.1Hz,4H),7.8(s,2H),7.7(d,J =9.3Hz,0.3H),7.6(s,2H),7.4(t,J=7.1Hz,1H),7.2-6.9(m,4H),6.8-6.7(m,1H),3.1(s,0.4H).

[0092] The preparation method of cross-linked polyaromatic amide is as follows: linear polyaromatic amide is fully dissolved in NMP to prepare a 40 mg / mL polymer solution, and then dripped onto a clean substrate. After the solvent evaporates, the solution is dried at 110° C. for 10 hours, and the film is peeled off from the substrate to obtain a self-supporting film. The film is thermally cured at 270° C. for 6 hours under nitrogen, and annealed at 300° C. for 10 hours, and then cooled to obtain the cross-linked polyaromatic amide.

[0093] Performance Testing:

[0094] The specific synthesis route of the aromatic diamine containing benzocyclobutene is shown in the following formula:

[0095]

[0096] The 3-[2,5-bis-(4-aminophenoxy)-phenyl]-bicyclo[4.2.0]-octa-1,3,5-triene obtained in Example 2 was subjected to a nuclear magnetic resonance test. Figure 1 shown.

[0097] The linear polyaromatic amides obtained in Examples 4-8 were subjected to nuclear magnetic resonance testing. Figure 2 As shown. According to the molar ratio of 3-[2,5-bis-(4-aminophenoxy)-phenyl]-bicyclo[4.2.0]-oct-1,3,5-triene / 3,4'-ODA / TPA, the content of benzocyclobutene structural units in polyaromatic amide can be calculated by integrating the characteristic peak signal (3.12ppm) of the aliphatic region of benzocyclobutene in the hydrogen nuclear magnetic resonance spectrum. Since cross-linked polyaromatic amide is insoluble, no nuclear magnetic resonance data was measured. This is because polyaromatic amide with good solubility and thermal stability can be prepared by introducing flexible segments such as ether bonds or side groups that destroy the regularity of the molecular chain into the molecular structure of rigid linear polyaromatic amide.

[0098] The linear and cross-linked polyaromatic amides obtained in Examples 4-8 were subjected to TGA tests, and the results are shown in Table 1. d 5％ The window is 378-403℃, T d 10％ The window is 452-467℃; the T d 5％ The window is 421-442℃, T d 10％ The window is 487-489℃. After the linear polyaromatic amide is cross-linked, a cross-linked network of tetrahydrodibenzocyclooctadiene (DBCOD) structure is formed between the molecular chains, which improves the thermal stability of the polymer, T d 5％ The average rise is 36°C, T d 10％The average increase is 30°C. Example 4 Comparison of linear and cross-linked polyaramids Figure 3 shown.

[0099] Table 1 Thermal weight loss temperature of each example series of benzocyclobutene molar ratio of linear polyaromatic amide

[0100]

[0101] The linear and cross-linked polyaromatic amides obtained in Examples 4-8 were subjected to DSC testing. The results are as follows: Figure 4 and Figure 5 As shown. The DSC curve clearly shows the thermosetting behavior of a series of linear polyaromatic amides containing benzocyclobutene, and then determines the temperature parameters for preparing cross-linked polyaromatic amides, whose [4+4] ring opening temperature is 274-294°C. No glass transition temperature was observed for this series of linear and cross-linked polyaromatic amides.

[0102] The cross-linked polyaromatic amide obtained in Examples 4-8 was subjected to XRD test, and the results were as follows: Figure 6 As shown. Before and after the cross-linking of polyaromatic amide, only the peak intensity decreases, and its amorphous morphology remains unchanged. The series of cross-linked polyaromatic amides all have broad peaks, indicating an amorphous morphology. Due to the introduction of more ether bonds and asymmetric monomers 3,4'-ODA, the rigidity of the molecular chain becomes smaller, the regularity is reduced, the tight stacking of the polymer chain is destroyed, and the macromolecule changes from a straight chain to a curled structure, causing the aggregation structure inside the polymer to change, resulting in a decrease in crystallinity. At the same time, the cross-linked network formed between the molecular chains increases the free volume of the polymer. These effects significantly reduce the crystallinity of the polymer.

[0103] The linear and cross-linked polyaromatic amides obtained in Examples 4-8 were tested by nanoindenter, with a force of 50 μN applied, the sample size was 25×25 mm, and the thickness was 22±2 μm. The results are shown in Table 2. The changes in the hardness and Young's modulus of the series of polyaromatic amides before and after cross-linking were measured. The Young's modulus of linear polyaromatic amides is 4.13-7.56 GPa, and the hardness is 0.21-0.63 GPa; the Young's modulus of cross-linked polyaromatic amides is 6.48-7.46 GPa and the hardness is 0.21-0.65 GPa. Example 4 is a binary polymer with a high degree of regularity. The cross-linking network formed by the ring opening of benzocyclobutene enhances the modulus and hardness. The mechanical properties of Examples 5-7 are reflected in the fact that the modulus and hardness of the series of linear polyaromatic amides are greater than those of the series of cross-linked polyaromatic amides, which is attributed to the cross-linking network formed by the ring opening of benzocyclobutene, which destroys the hydrogen bonds between the molecular chains, resulting in a decrease in Young's modulus and hardness. In Example 8, the third monomer 3,4'-ODA accounts for a large proportion and has a lower molecular rigidity than the benzocyclobutene structure, resulting in a decrease in the molecular strength of the linear polymer. The formation of a cross-linked network enhances the mechanical properties of the polymer, and all Young's modulus and hardness are improved. Figure 7Nanoindenter loading and unloading curves before and after crosslinking of Example 7.

[0104] Table 2 Young's modulus and hardness of each example

[0105]

[0106] The cross-linked polyaramid obtained in Examples 4-8 was subjected to TMA test using a tensile mode at a test temperature of 25-200°C. The results are as follows: Figure 8 It can be seen that the CTE (25-150°C) of Examples 6 and 7 is -1.2, -11.0×10 - 6 K -1 The negative value indicates the occurrence of thermal shrinkage effect. The CTE (25-150℃) of the series of cross-linked polyaramid samples (except Example 7) is -1.2-4.3×10 -6 K -1 , close to zero expansion coefficient, has potential applications in many fields that strictly require dimensional accuracy; CTE (25-200℃) is 15.1-17.9×10 -6 K -1 , close to the CTE value of Cu, and may be used in the fields of optics, energy and microelectronics. In summary, the CTE window of the series of cross-linked polyaramid is -11.0-17.9×10 -6 K -1 This material with low CTE and wide window can be adapted to specific applications. The deformation rate is -1.37-3.12‰, and it has good material dimensional stability. The specific data is shown in Table 3.

[0107] Table 3 CTE and deformation rate of cross-linked polyaramid in each embodiment

[0108]

[0109]

[0110] This series of polyaramid has good film-forming properties, and the polyaramid film has good flexibility and transparency. Fig. 9 shown.

[0111] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. An aromatic diamine containing benzocyclobutene, characterized in that: The structure is:

2. The method for preparing an aromatic diamine containing benzocyclobutene according to claim 1, characterized in that: The following steps are involved: Under nitrogen protection, 3-[1,4-benzenediol]-bicyclo[4.2.0]-octa-1,3,5-triene and 4-nitrochlorobenzene are dissolved in an amide organic solvent or a pyrrolidone organic solvent and reacted under alkaline conditions to obtain a dinitro compound containing benzocyclobutene; The dinitro compound containing benzocyclobutene is dissolved in an ester organic solvent and then reduced under a hydrogen atmosphere to obtain an aromatic diamine compound containing benzocyclobutene.

3. The method for preparing an aromatic diamine containing benzocyclobutene according to claim 2, characterized in that: The specific method of the reaction under alkaline conditions is: dissolving potassium carbonate or sodium carbonate in a first organic solvent to form alkaline conditions, the molar number of potassium carbonate or sodium carbonate is 2-2.5 times that of 3-[1,4-benzenediol]-bicyclo[4.2.0]-octa-1,3,5-triene, the reaction temperature is 80-130° C., and the reaction time is 5-10 hours.

4. The method for preparing an aromatic diamine containing benzocyclobutene according to claim 2, characterized in that: The specific method of reducing the dinitro compound containing benzocyclobutene under a hydrogen atmosphere is: adding a Pd / C catalyst to the dinitro compound containing benzocyclobutene, wherein the amount of Pd in ​​the Pd / C catalyst is 5-10‰wt% of the dinitro compound containing benzocyclobutene; The molar ratio of the 3-[1,4-benzenediol]-bicyclo[4.2.0]-octa-1,3,5-triene to 4-nitrochlorobenzene is 1:2.0-2.

3.

5. A linear polyaramid, characterized in that The structure is as follows: x is 1-50, y is 0-49.

6. A cross-linked polyaramid, characterized in that: The structure is as follows: x is 1-50, y is 0-49.

7. The method for preparing linear polyaromatic amide according to claim 5, characterized in that: The following steps are involved: Aromatic diamine containing benzocyclobutene, terephthalic acid, 3,4'-ODA and CaCl2 or LiCl are added into a reaction container, and after nitrogen substitution, P(OPh)3, pyridine and NMP are added for reflux reaction to obtain linear polyaromatic amide.

8. The method for preparing the cross-linked polyaramid according to claim 6, characterized in that: The following steps are involved: Aromatic diamine containing benzocyclobutene, terephthalic acid, 3,4'-ODA and CaCl2 or LiCl are added into a reaction container, and after nitrogen substitution, P(OPh)3, pyridine and NMP are added for reflux reaction to obtain linear polyaromatic amide; Under inert gas conditions, the linear polyaromatic amide is thermally cured and then annealed to obtain a cross-linked polyaromatic amide containing a tetrahydrodibenzocyclooctadiene structure.

9. The method for preparing the linear polyaromatic amide according to claim 7 or 8, characterized in that: The reflux reaction is carried out at 100-150° C. for 12-24 hours; The molar ratio of the total amount of the aromatic diamine containing benzocyclobutene, 3,4'-ODA, terephthalic acid, CaCl2, P(OPh)3, and pyridine is 1:1:(2-5):(4-8):(6-12).

10. The method for preparing cross-linked polyaramid according to claim 8, characterized in that: The specific method of annealing the linear polyaramid after heat curing is as follows: The linear polyaramide is heated to 270° C. for thermal curing for 6-10 hours, and annealed at 300° C. for 12-20 hours.

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