9-phenoxy-10-phenylanthracene structure modified PMIA and a preparation method thereof

Abstract

The application discloses a 9-phenoxy-10-phenyl anthracene structure modified PMIA and a preparation method thereof. The 9-phenoxy-10-phenyl anthracene structure modified PMIA has the following molecular structural formula: wherein n / (n+m) = 0.20-0.80. Compared with PMIA, the 9-phenoxy-10-phenyl anthracene structure modified PMIA can improve the heat resistance, film flexibility, light transmittance, hydrophilicity and the like of PMIA by introducing a 9-phenoxy-10-phenyl anthracene structure to modify PMIA, and thus a modified PMIA with excellent comprehensive performance is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to a modified PMIA, in particular to a 9-phenoxy-10-phenyl anthracene structure modified PMIA, and also to a preparation method thereof, and belongs to the technical field of high polymer materials. BACKGROUND

[0002] PMIA is a high-performance wholly aromatic polyamide, which is synthesized by interdiaminophthaloyl chloride (or interdiaminophthalic acid) and m-phenylenediamine. Nomex is the first commercialized PMIA, which was invented by DuPont in 1967. From the molecular structure, PMIA is a wholly aromatic linear macromolecule with zigzag arrangement, which is directly connected by interphenyl and amide bond. This connection mode leads to no conjugation effect of covalent bond, small internal rotation potential of molecular chain, and flexible molecular structure. The crystal structure of PMIA is the most stable structure under the interaction of intramolecular force, which belongs to triclinic system. PMIA cannot be completely extended chain conformation due to the high torsional potential barrier of C-N and amide bond and the strong intermolecular hydrogen bond, and the length of molecular c-axis is about 9% shorter than that of the extended conformation, and there is chain torsion in the molecule, and the dihedral angle is 30°.

[0003] Such structure determines that PMIA material has excellent flame retardancy (LOI is about 28, no dripping, and is a self-extinguishing material), thermal performance (glass transition temperature is 270-290℃, and starts to decompose at 370℃), good chemical stability (resistant to most high-concentration inorganic acids), strong mechanical processing characteristics, and excellent electrical insulation (dielectric constant close to air), and other advantages. As a flame-retardant material (such as heat-resistant military uniforms, fire-fighting clothes, and high-temperature protective clothing), high-temperature filtration material (high-temperature resistant filter bag and filter felt, etc.), honeycomb material (multi-layer plywood), and electrical insulation material (insulating paper, etc.), PMIA is widely used in the fields of national defense and military, fire fighting, high-temperature filtration, aerospace, transportation, and electronics.

[0004] Although PMIA has excellent performance superior to ordinary organic polymer fibers, the regular stacking structure of benzene rings in the molecular chain, and the firm and highly directional intermolecular hydrogen bond also lead to the rigidity of PMIA molecular chain, which affects the comfort of the material in practical application. And the structure feature that the amide bond is connected in the meta position makes the covalent bond have no conjugation effect, so that the surface of the molecular chain lacks polar groups, and the surface wetting performance of the material is poor, thereby limiting its practicality. At present, researchers have made extensive research on enhancing the flexibility and activity of the material, and have made great progress. The modification methods mainly include the following:

[0005] (1) Surface modification method: This method activates the benzene ring structure in PMIA through special methods such as nitration, sulfonation or direct fluorination. It can also use polar groups such as grafted amino groups and hydroxyl groups to improve fiber wettability and comfort. However, these methods will degrade aramid to a certain extent and reduce mechanical properties. Therefore, in recent years, some researchers have proposed a PMIA surface activation method based on the Friedel-Crafts reaction. The reaction conditions of this method are mild and the damage to the fiber is small. ("Friedel-Crafts alkylation modification and hydrophilic soft finishing of meta aramid", Wei X, et al. Journal of Engineered Fibers and Fabrics, 2021, 16: 1558925021999061) discloses the modification of aramid with epichlorohydrin and then treating the sample with a hydrophilic softening agent to improve the comfort of the fabric. The results show that the surface wettability of the modified fabric is significantly improved, the bending rigidity is reduced by 39%, and the flame retardancy is also improved to a certain extent. The modified fabric also has excellent wash fastness, with little performance degradation after 40 washing cycles.

[0006] (2) Blending modification: Blending modification refers to a modification method that uses meta-aramid to blend with other fiber materials such as cotton, wool, polyacrylonitrile, polyester, and flame-retardant viscose. Generally, improved fibers with flame retardant properties are used for blending to prevent the flame retardancy of the material from being reduced due to fiber blending. For example, the Nomex III series products are blended with 5% Kevlar and 95% Nomex, which improves the shortcomings of pure Nomex fiber fabrics, such as the high thermal shrinkage rate of the material, which makes the fabric easy to break at high temperatures and reduces heat resistance.

[0007] (3) Copolymerization modification: Copolymerization modification refers to the addition of a third or fourth monomer to the polymerization system of m-phenylenediamine and isophthaloyl chloride (or isophthalic acid) for polycondensation. Different substituents can be introduced according to the requirements of different polymer modifications. Co-condensation modification is one of the simplest and most effective modification methods. For example, the addition of a third monomer containing halogen or phosphorus in the polycondensation reaction improves the flame retardancy of aromatic polyamides while maintaining good heat resistance.

[0008] To reduce the rigidity of the molecular chain, bulky side groups or long aliphatic chains are introduced into the polymer backbone. (“New polyamides based on diacid with decanediamide and methylene groups and aromatic diamines”, Diwate A V, et al. Journal of Applied Polymer Science, 2022, 139(21):52221) discloses the reaction of a new long-chain alkane aromatic diacid containing 8 methylene groups with various commercial aromatic diamines to synthesize a series of polyamides. Studies have found that the aliphatic C8 group in the molecule improves the flexibility of the chain, reduces the interaction and tight packing of the chain, but the initial degradation temperature of the polymer decreases slightly. (“Synthesis and characterization of flexible meta-aramid modified with 4,4’-methylenedianiline”. Hong W, et al. Macromolecular Chemistry and Physics, 2023, 224(17):2300100.) A series of modified copolyamides APMIA-n containing methylene groups in the main chain were synthesized, and the copolymers had good solubility in polar organic solvents such as DMF and DMSO, the flexibility of the thin film was significantly increased (the tensile modulus decreased from 4.62 GPa to 2.98 GPa), and the optical transparency was good, which expanded the application of PMIA in packaging, screen display and other fields.

[0009]

[0010] In recent years, monomers containing ether bonds have also been applied to the modification research of PMIA copolymerization. Literature (“Synthesis and characterization of easily colored meta-aramid copolymer containing ether bonds”, Li N, et al. Chinese Journal of Polymer Science, 2019, 37:227-234.) uses 3,4’-diamino diphenyl ether containing ether bonds and asymmetric structure as a modified third monomer, copolymerized with m-phenylenediamine and phthaloyl chloride, obtained copolymer OPMIA with different ether bond content, while maintaining high thermal decomposition temperature and mechanical properties, reduced the glass transition temperature of OPMIA, and the light transmittance was greater than 90%.

[0011]

[0012] Document (“Preparation and structure-property relationship of flexible aramid films with enhanced strength by introducing asymmetric and symmetric aromatic ether bond structures”, Hang Z, et al. Polymer Chemistry, 2023, 14(34): 3906-3915) discloses the introduction of 1,3-bis(4-aminophenoxy)benzene (MAPB) and 1,4-bis(4-aminophenoxy)benzene (PAPB) with asymmetric and symmetric aromatic ether bond structures into meta-aramid, studies the properties of copolymer films of different proportions of MAPB and PAPB, and finds that when their addition amount is 10%, the comprehensive improvement of film softness and tensile strength can be realized, while the thermal stability is maintained.

[0013]

[0014] Document (“Facile preparation and characterization of soluble aramid”, Zhou S, et al. Journal of Applied Polymer Science, 2018, 135(23): 4634159.) discloses the modification of meta-aramid by 2,6-dichloronaphthalene (26N-COCl), and the obtained copolymer NOM-n is soluble in NMP, DMF-LiCl and other organic solvents, has excellent thermal stability (T 5％ 460°C), and is easy to process into films, pipes, filament fibers and rod fibers, etc.; has excellent mechanical strength (tensile strength, tensile modulus and elongation at break are 75-139 MPa, 2.37-3.45 GPa and 5%-11%, respectively); has good optical properties (transmittance at 500 nm is 80%) and fluorescence.

[0015]

[0016] Document ("Facile synthesis and characterization of soluble aramid containing polar-hydroxyl side group", Yan G, Wang H.Polymer, 2022, 238: 124411) discloses that a copolyamide PA-OH is prepared by introducing an asymmetric structure in a polyaramid using a copolymerization method and modifying by introducing a hydroxyl side group, which reduces the conjugation of the polymer main chain and has excellent solubility in polar solvents, and the processability is improved.

[0017]

[0018] In summary, the modification methods reported in the prior art are difficult to obtain modified PMIA with good comprehensive performance. For example, the rigidity of the PMIA molecular chain and the surface wetting performance of the material are poor, and there is a contradiction between high tensile strength and high flexibility, which is difficult to improve simultaneously. SUMMARY

[0019] In view of the defects of the prior art, the first object of the present application is to provide a 9-phenoxy-10-phenylanthracene structure modified PMIA. Compared with PMIA, the heat resistance, flexibility of the film, light transmittance, hydrophilicity, etc. of PMIA can be improved by introducing a 9-phenoxy-10-phenylanthracene structure to modify PMIA, and a modified PMIA with excellent comprehensive performance is obtained.

[0020] The second object of the present application is to provide a preparation method of 9-phenoxy-10-phenylanthracene structure modified PMIA. The method is simple to operate and mature in process, and is conducive to large-scale production.

[0021] In order to achieve the above technical purpose, the present application provides a 9-phenoxy-10-phenylanthracene structure modified PMIA, which has the following molecular structure formula:

[0022]

[0023] Wherein, n / (n+m) = 0.20-0.80.

[0024] The existing PMIA molecular chain has rigidity and poor surface wetting performance, thereby affecting its practicability, mainly based on the regular stacking structure of benzene ring in the PMIA molecular chain, firm and highly directional intermolecular hydrogen bond and amide bond connected in the meta position to make the covalent bond have no conjugation effect and other characteristics. The key of the present application lies in that 9-phenoxy-10-phenyl anthracene structure is used as a modified unit, which is introduced into the PMIA molecular chain through copolymerization, on the one hand, the asymmetric structure can effectively destroy the regularity of the molecular chain, so that the optical performance, flexibility and solubility of the polymer are improved, and the polar ether bond can improve the surface wettability of the polymer to a certain extent; on the other hand, the introduction of the anthracene structure with good stability can further increase the thermal decomposition temperature of PMIA, and thirdly, the 9-phenoxy-10-phenyl anthracene structure is used as a large volume and long chain unit, which is completely different from the size and chain length of the isophthalic acid unit structure, so that the density of the amide bond is reduced, the long-range ordered structure of the polyamide molecular chain can be broken, the crystallinity is further reduced, and the copolymer tends to be amorphous structure, which is very effective for improving the performance of PMIA.

[0025] As a preferred scheme, n / (n+m) in the molecular structure formula is 0.40-0.60. The introduction of 9-phenoxy-10-phenyl anthracene structure is very obvious for improving the performance of PMIA, such as flexibility, transparency and hydrophilicity, but with the increase of the number of 9-phenoxy-10-phenyl anthracene structure, the tensile strength of PMIA is lost to a certain extent and the glass transition temperature is increased. Therefore, n / (n+m) in the molecular structure formula is further preferably 0.40-0.60.

[0026] As a preferred scheme, the number average molecular weight of the 9-phenoxy-10-phenyl anthracene structure modified PMIA is 20-40 thousand, and the molecular weight distribution index is 1.0-2.0.

[0027] The present application also provides a preparation method of the 9-phenoxy-10-phenyl anthracene structure modified PMIA, which is that 9-(4-carboxyphenoxy)-10-(4-carboxyphenyl) anthracene, isophthalic acid and m-phenylenediamine are subjected to polymerization reaction through Yamazaki phosphine method, and then the product is obtained.

[0028] As a preferred scheme, the molar percentage composition of 9-(4-carboxyphenoxy)-10-(4-carboxyphenyl) anthracene and isophthalic acid is 20-80%: 20-80%. As a more preferred scheme, the molar percentage composition of 9-(4-carboxyphenoxy)-10-(4-carboxyphenyl) anthracene and isophthalic acid is 40-60%: 40-60%.

[0029] As a preferred embodiment, the total molar amount of 9-(4-carboxyphenoxy)-10-(4-carboxyphenyl)anthracene and isophthalic acid is equal to that of m-phenylenediamine.

[0030] As a preferred embodiment, the polymerization reaction conditions are: first raising the temperature to 75-85°C, then slowly raising the temperature to 115-125°C over 2.5-3.5 hours, and maintaining the temperature for 4-8 hours. Controlling the polymerization reaction conditions can help improve monomer conversion and produce copolymers with relatively high molecular weight.

[0031] The Yamazaki phosphonyl method involved in the present invention is a well-known method in the prior art, which mainly uses triphenyl phosphite as a catalyst, chloride salt as a water absorbent, and pyridine as a solvent and dehydrating agent.

[0032] Compared with the prior art, the present invention has the following beneficial technical effects:

[0033] 1) The 9-phenoxy-10-phenylanthracene structure-modified PMIA of the present invention has the following significant advantages over PMIA: Based on the characteristics of the 9-phenoxy-10-phenylanthracene structure, such as a large conjugated system, asymmetric structure, and ether oxygen bonds, it is introduced into the PMIA molecular chain to obtain an amorphous modified PMIA with low crystallinity. The heat resistance, film flexibility, light transmittance, hydrophilicity and other properties of PMIA can be improved.

[0034] 2) The method for preparing the 9-phenoxy-10-phenylanthracene structure-modified PMIA of the present invention is simple to operate, has a mature process, and is conducive to large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is the H NMR spectrum of M1.

[0036] Figure 2 This is the carbon NMR spectrum of M1.

[0037] Figure 3 is the infrared absorption spectrum of M1.

[0038] Figure 4 Comparison of hydrogen nuclear magnetic resonance spectra of polyamides: (a) PMIA, (b) PA5, and (c) PA-50.

[0039] Figure 5 This is the hydrogen nuclear magnetic resonance spectrum of PA-50.

[0040] Figure 6 is the infrared absorption spectrum of PMIA / PA5-n.

[0041] Figure 7 This is the wide-angle X-ray diffraction curve of PMIA / PA5-n.

[0042] Figure 8 This is the thermogravimetric curve of PMIA / PA5-n in N2.

[0043] Figure 9 This is the differential scanning calorimetry curve of PMIA / PA5-n in N2.

[0044] Figure 10 This is the stress-strain curve of PMIA / PA5-n film.

[0045] Figure 11 is the UV-visible transmission spectrum of PMIA / PA5-n film.

[0046] Figure 12 is the static contact angle of PMIA / PA5-n film. DETAILED DESCRIPTION

[0047] The following specific examples are intended to further illustrate the present invention, rather than to limit the scope of protection of the claims.

[0048] Unless otherwise specified, the chemical reagents involved in the following specific examples are conventional commercially available reagents.

[0049] H NMR, C NMR ( 1 H NMR, 13 C NMR: Spectra were measured on a Bruker-Avance 400 MHz NMR spectrometer using deuterated dimethyl sulfoxide and deuterated chloroform as solvents and tetramethylsilane (TMS) as the internal standard.

[0050] Infrared spectroscopy (FT-TR): A Fourier transform infrared spectrometer (Perkin-Elmer Spectrum One FTIR) made in the United States was used, potassium bromide was used as the background, the sample was pressed into a thin slice, and the sample was measured at 4 cm -1 Under the condition of high resolution, the range is 500~4000cm -1 Scanned 64 times.

[0051] Ultraviolet-visible absorption spectroscopy (UV-Vis) test: On a Hitachi U-3100 spectrophotometer, the sample was prepared to about 10 -5 The test range of the test liquid is 200-600nm.

[0052] Differential Scanning Calorimetry (DSC): A Perkin-Elmer (DSC 800) instrument was used for the test. 5.5-10.0 mg of sample was pressed into an aluminum crucible and the temperature was raised from 30°C to 400°C (depending on the temperature at which 5% thermal weight loss of the sample was achieved) at a heating rate of 20°C / min in a nitrogen atmosphere with a flow rate of 20 mL / min.

[0053] Thermogravimetric analysis (TGA) was performed using a Diamond TG / DTG-6300 instrument from PE (USA) with a nitrogen flow rate of 200 mL / min. 1-5 mg of sample was placed in an alumina crucible. The sample was tested in nitrogen starting at 30°C and the temperature was raised to 800°C at a rate of 10°C / min.

[0054] Wide-angle X-ray Diffraction (WARD): Measured on a Rigaku D / max 2550VB / PC X-ray diffractometer. Films were cut into 1 cm x 1 cm samples. Operating voltage: 40 kV, radiation source: Cu / Ka, current: 40 mA, scanning frequency: 20° / min, scanning between 5 and 60°.

[0055] Relative molecular weight test (GPC): DMF was used as the solvent and eluent, PMMA was used as the standard sample, and the test was performed on an Agilent 1260 Infinity II gel permeation chromatograph at a flow rate of 0.1 mL / min. The sample solution was filtered through a filter with a pore size of 0.24 μm.

[0056] Saturated water absorption (Mt): The film was tested for saturated water absorption using the GB / T1034 standard. Before testing, the sample was cut into films with a length, width, and thickness of 30mm*30mm*35μm and dried in a vacuum oven at 120°C for 48 hours to a constant weight (m0). The film was then placed in water and weighed at room temperature every 12 hours until the mass stopped increasing, which was recorded as m0. t Each sample was tested 3 times and the average value was taken. (Mt=(m t -m0) / m0×100wt%)

[0057] Contact angle (CA): The film was cut into 1 cm*4 cm samples to be tested, fixed on a glass slide, and tested using a contact angle tester model DSA25 produced by KRUSS, Germany, with deionized water as the test liquid.

[0058] Solubility (S): 10 mg of polyamide sample was added to 1 mL of different organic solvents, and the solubility of the polymer was tested at room temperature and 70°C. The solubility state can be classified as insoluble (---), partially soluble upon heating (+--), completely soluble upon heating (++-), and completely soluble at room temperature (+++).

[0059] Mechanical properties of polymer films: The tensile properties of the films were tested on an AG 22000 universal electronic testing machine (Shimadzu, Japan). The films were cut into samples of 4 cm*0.6 cm and tested at room temperature with a tensile rate of 10 mm / min. The average of three test results was taken.

[0060] Transmittance test (T): The transmittance of the film was tested according to GB / T2410-2008 using a Hitachi U-3100 ultraviolet spectrophotometer, the film was cut into an area of 4 cm*1 cm, a thickness of 30-40 um, a slit of 1 nm, and a wavelength of 200-800 nm.

[0061] Example 1

[0062] Preparation of 9-(4-carboxyphenoxy)-10-(4-carboxyphenyl)anthracene (abbreviated as M1):

[0063]

[0064] Anthrone (38.8 g, 0.2 mol), p-fluorobenzonitrile (53.24 g, 0.44 mol), potassium tert-butoxide (44.8 g, 0.4 mol), and 400 mL of DMF were added to a 1000 mL three-necked flask. The reaction was carried out at 140°C for 50 h under N2. After complete reaction, the reaction system was cooled to room temperature in a refrigerator, and slowly poured into 400 mL of water under stirring to obtain a yellow-brown viscous liquid. 200 mL of glacial acetic acid was added, and stirred until it was no longer viscous. Filtration was performed, and the product was washed with water until it was neutral to obtain a yellow crude product. Vacuum drying was performed for 12 h, and recrystallization was performed with DMF to obtain 66.9 g of green block-shaped crystal M2, with a yield of 84.5%, and a melting point of about 276-287°C. 1 H NMR (400 MHz, CDC13): δ (ppm) = 7.97 (d, J = 8.7 Hz, 2H), 7.85 (d, J = 7.8 Hz, 2H), 7.54 (d, J = 7.8 Hz, 2H), 7.50 (d, J = 8.6 Hz, 4H), 7.430 (t, J = 7.2 Hz, 2H), 7.34 (t, J = 7.2 Hz, 2H), 6.88 (d, J = 8.4 Hz, 2H).

[0065] M2 (3.96 g, 10 mmol), potassium hydroxide (6.15 g, 0.44 mmol), and an aqueous solution of ethanol 100 mL (V 乙醇 水 = 1:1) were added to a 250 mL round-bottom flask. The reaction was carried out at 100°C for 24 h under condensation reflux until all the solid in the solution was dissolved. After the reaction was completed, the reaction system was hot-filtrated, and the filtrate was poured into 200 mL of water. The pH of the solution was adjusted to 1 with concentrated hydrochloric acid. Filtration was performed, and the product was washed with water until it was neutral to obtain a yellow-green solid. Vacuum drying was performed for 12 h, and recrystallization was performed with cyclohexane and DMF at room temperature to obtain 2.31 g of light yellow needle-shaped crystal M1, with a yield of 53.2%. 1 ​H NMR (400 MHz, DMSO-d6): δ (ppm) = 12.99 (s, 2H), 8.24 (d, J = 8.1 Hz, 2H), 8.05 (d, J = 8.6 Hz, 2H), 7.93 (d, J = 8.8 Hz, 2H), 7.68-7.59 (m, 4H), 7.55 (t, J = 8.4 Hz, 2H), 7.50 (t, J = 8.4 Hz, 2H), 6.96 (d, J = 8.8 Hz, 2H). 13 C NMR (100 MHz, DMSO-d6): δ (ppm) = 167.72, 167.16, 163.34, 144.76, 142.72, 134.38, 132.39, 131.91, 130.92, 130.45, 130.11, 127.02, 126.96, 125.31, 124.06, 122.08, 115.55.

[0066] Example 2

[0067] Synthesis of copolyamides containing 9-phenoxy-10-phenylanthracene structure (PMIA / PA5-n):

[0068]

[0069] The m-phenylenediamine (MPD) (0.432 g, 4 mmol) was accurately weighed by an analytical balance, and M1 and IPA were accurately weighed according to the ratio in Table 1, using compound M1 as a modified monomer, a series of terpolymers containing different contents of 9-phenoxy-10-phenylanthracene structure (PMIA / PA5-n) were synthesized by changing the ratio of two diacid monomers and m-phenylenediamine using the "Yamazaki" phosphine method, and the synthesis route is shown above.

[0070] As an example, polyamide PA-50 was synthesized by the similar method as follows: M1 (0.868 g, 2 mmol) and isophthalic acid (IPA) (0.332 g, 2 mmol), calcium chloride (1.2 g), lithium chloride (0.8 g), 4 mL of triphenyl phosphite, 2 mL of pyridine were added into a 100 mL three-necked flask in sequence. Under N2, m-phenylenediamine (MPD) (0.4324 g, 4 mmol), 10 mL of NMP were added quickly, keeping the flask closed. The mixture was stirred at 80 °C, and the temperature was programmed to 120 °C in 3 h, keeping at 120 °C for 6 h. After the reaction was stopped, the obtained viscous solution was poured into 100 mL of ethanol under stirring, obtaining a light yellow fibrous solid. The solid was extracted by Soxhlet for 24 h, and then dried in vacuum for 48 h, obtaining 1.466 g of PA-50 with a yield of 98.5%. Polyamide film was prepared by casting method. 3 mL of NMP and 0.12 g of polyamide were added into a reagent bottle, and the bottle was put into an oven. After the sample was dissolved completely, the homogeneous solution was cast on a 4*4 cm 2 glass plate from the middle, and the plate was put into an oven at 80 °C for drying for 12 h. After no obvious solvent, the film was cooled to room temperature naturally, and demoulded by distilled water, and then put into a vacuum drying oven at 120 °C for 12 h, obtaining a light yellow film.

[0071] 1 H NMR (400 MHz, DMSO-d6): δ (ppm) = 10.55 (d, J = 13.3 Hz, 6H), 10.25 (t, J = 14.2 Hz, 2H), 8.58 (d, J = 14.0 Hz, 2H), 8.49 (s, 1H), 8.41 (s, 1H), 8.36-8.24 (m, 5H), 8.17 (d, J = 6.6 Hz, 5H), 8.09 (d, J = 7.6 Hz, 4H), 7.96 (d, J = 8.0 Hz, 4H), 7.75-7.64 (m, 11H), 7.61-7.51 (m, 13H), 7.38 (d, J = 7.4 Hz, 5H), 7.23 (s, 1H), 7.00 (d, J = 6.8 Hz, 4H).

[0072] As an example, the structure of polymer PA-50 was analyzed, and it can be seen from Figure 4 and Figure 5 that, since PA-50 is synthesized by copolymerization of three different monomers, the peaks No. 1 and No. 2 at 10.2 ppm and 10.5 ppm are the proton vibration peaks in the amide bonds of the two diacids, and the peak area ratio S H1 :S H2=6:2. This is because isophthalic acid is meta-substituted, and the carboxyl group on the metaphenyl group forms an amide bond with the amino group. The distance between the amide bonds is very close, and the hydrogen protons will affect each other, causing the chemical shift to move downfield. Under the influence of the electron-withdrawing inductive effect of the anthracene ring, the chemical shift of the hydrogen (H1) on the amide bond that is not close to the ether bond end of the asymmetric diacid becomes larger, and the proton peak overlaps with the hydrogen proton peak of the amide bond formed by meta-phenylenediamine isophthalic acid. Meanwhile, the H2 on the amide bond at the other end of the asymmetric diacid is affected by the electron-donating inductive effect, and the chemical shift shifts upfield. Peak 2 appears to the right of peak 1, and the peak intensity increases with the increase of the asymmetric structure content. The chemical shifts and hydrogen numbers of the remaining proton peaks in the hydrogen spectrum are consistent with the polymer structure, proving that the target polyamide was successfully synthesized.

[0073] Combine Figure 4 It was found that PMIA ( Figure 4 In a) there is a single peak at 10.515ppm, which is the proton vibration peak in the amide bond; PA5 without isophthalic acid ( Figure 4 b) The main chain contains an asymmetric structure, so there are two overlapping single peaks at around 10.2ppm and 10.5ppm, and the integrated area ratio is 1:1. These are the proton vibration peaks of the four hydrogens in the amide bond. Therefore, for copolyamide PA-50, the absorption area S H1 and S H2 The actual proportion F of PA5 components in the copolymer can be calculated PA5 , the specific data are listed in Table 1:

[0074] Table 1 Feed ratio of reactants and actual content of PA5 segments in PMIA / PA5-n

[0075]

[0076] a The number of copolymer units, where n represents the feed ratio of M1 in the polymer.

[0077] b Feed ratios of dibasic acid monomer M1, IPA acid, and MPD.

[0078] c The integrated area of ​​H1.

[0079] d The integrated area of ​​H2.

[0080] e The actual proportion of PA5 components contained in the copolymer.

[0081] Depend on Figure 6 It can be seen that in the range of 3100-2800cm -1The broad absorption band at 3316 cm-1 disappears, and the stretching vibration of NH in the amide group is at 3316 cm-1. -1 A broad peak appears around 1662 cm; Amide I band: stretching vibration of C=O bond at 1662 cm -1 Amide II band: NH in-plane bending vibration at 1531cm -1 Appears at; Amide III band: CN stretching vibration absorption peak at 1301cm -1 It appears at 1599cm, which shows that the polymer contains amide bonds; and the C=C stretching vibration is at 1599cm -1 and 1492cm -1 It appears at 1167cm -1 There is an absorption peak at , which is the stretching vibration peak of COC, while pure PMIA has no absorption peak here. Moreover, the absorption peak intensity increases with the increase of PA5 segment content, proving that the 9-phenoxy-10-phenylanthracene structure has been successfully introduced into the polyamide. In summary, it can be fully demonstrated that the target copolyamide was successfully synthesized.

[0082] Table 2 Molecular weight and yield of PMIA / PA5-n

[0083]

[0084]

[0085] Table 2 shows that the weight-average molecular weight of the PMIA / PA5-n copolymer ranges from 36,799 to 49,509 g / mol, the number-average molecular weight ranges from 20,885 to 38,983 g / mol, and the polydispersity index (PDI) remains between 1.14 and 1.91, indicating that this series of polyamides has a high molecular weight and a concentrated molecular weight distribution. This series of polyamides also exhibits a high yield, consistently exceeding 96.50%.

[0086] Depend on Figure 7 It can be seen that the WARD curves of the copolyamide PMIA / PA5-n are all broad and blunt dispersion peaks. This is because there are large-volume distorted non-coplanar 9-phenoxy-10-phenylanthracene structures in the main chain and the copolymerization method can break the order of the long chain of the polymer, reduce the interaction force between the polyamide molecular chains, destroy the regularity of the molecular chain stacking, and the polymer tends to an amorphous structure, indicating that the polymer has good optical properties and solubility.

[0087] Table 3 Solubility of PMIA / PA5-n in different solvents

[0088]

[0089] Table 3 shows that the introduction of asymmetric structures containing ether bonds into the molecular chain improves the solubility of the copolymer. Pure PMIA and copolyamide PMIA / PA5-n containing varying proportions are soluble in high-boiling-point, highly polar, aprotic solvents such as DMAc and NMP at room temperature, but insoluble in chloroform. Pure PMIA dissolves in DMF and DMSO upon heating, and is slightly soluble in THF. Increasing the asymmetric structure content to 30% allows the copolyamide to rapidly dissolve in DMF, Py, DMSO, and THF at room temperature. This is primarily due to the introduction of asymmetric, twisted, non-coplanar bulk structures into the polymer backbone, which increases the free volume of the molecular chain, facilitating diffusion of solvent molecules within the chain and improving the solubility of the polymer in the solvent. This excellent solubility makes the copolyamide PMIA / PA5-n easy to process even at relatively low temperatures, suggesting potential applications in advanced microelectronics and flexible displays.

[0090] Table 4 Thermal performance data of PMIA / PA5-n

[0091]

[0092] Depend on Figure 8 From the analysis of Table 4, we can see that pure PMIA starts to lose weight at 371℃, the temperature corresponding to the maximum decomposition rate is 459.7℃, and the carbon residue rate is 59.0% at 800℃. PMIA / PA5-n starts to lose weight at 381~434℃, and the T 5％ The thermal stability of PMIA / PA5-n increases with increasing asymmetric structure content. At 800°C, the residual carbon content of PMIA / PA5-n remains relatively stable, remaining between 60% and 69%, demonstrating the excellent thermal stability of this polymer series. This is because PMIA / PA5-n is an aromatic copolyamide, and the large, rigid anthracene groups introduced into the copolyamide provide a stable molecular structure that resists decomposition at high temperatures. Therefore, a higher content of 9-phenoxy-10-phenylanthracene structures improves the thermal performance of the copolyamide.

[0093] according to Figure 9 From the data analysis of Table 4, we can see that pure PMIA has only one glass transition temperature (T g =277.2℃). When the content of 9-phenoxy-10-phenylanthracene structure in copolyamide PMIA / PA5-n is 20%, its glass transition temperature (T g= 280.7 °C) is also one; with the increase of the structure content, the Tg of PMIA / PA5-n gradually increases, two glass transition temperatures appear in the DSC curve, the first glass transition temperature is between 285.7-311.4 °C, and the second glass transition temperature is between 288.8-314.8 °C, which has excellent thermal performance. This is because the large rigid anthracene structure is introduced into the main chain, and with the increase of the anthracene structure content, the proportion of single bond that can rotate in the main chain decreases, which makes the molecular chain rigid and the glass transition temperature increases. The DSC curve appears two absorption peaks and the difference between them is 2-5 °C, mainly because the series of polymers are amorphous wholly aromatic copolyamides, due to the relatively difficult movement of molecular chain, the imperfect crystal structure is melted first in the process of slow heating, forming local melting, and the unmelting crystal as nucleation point provides nucleation condition for the melt, because the heating speed is slow, those melts have time to recrystallize, and then melt at higher temperature, so the melting double peaks appear.

[0094] From Figure 10 As can be seen from Table 5, the elastic modulus of pure PMIA is 4.21 GPa, the tensile strength reaches 113.40 MPa, and the elongation at break is 4.7%. The elastic modulus of PMIA / PA5-n is 4.40-3.40 GPa, the tensile strength is 78.52-112.85 MPa, and the elongation at break is 6.9-20.3%; with the increase of the content of asymmetric segment PA5, the elongation at break shows an obvious upward trend (the maximum increase is 20.3%), and the tensile strength shows a downward trend, but the overall still maintains excellent mechanical properties to meet the actual use requirements; because the introduction of 9-phenoxy-10-phenyl anthracene structure not only reduces the density of amide bond in the molecular chain, but also reduces the intermolecular force, and destroys the crystallization performance of polyamide, the polymer tends to be amorphous structure, resulting in the tensile strength showing a downward trend; because the structure contains flexible ether bond, with the increase of the content of ether bond, the elongation at break of the polymer shows an upward trend; the elongation at break of PA-80 increases by 15.5% compared with pure PMIA, reaching 20.3%, which shows that the series of copolymers has excellent flexibility. The reason for the decrease of the elongation at break of PA-30 may be the low molecular weight. It is worth noting that the elongation at break of PA-20 increases by 2.1% without changing the tensile strength.

[0095] Table 5 Mechanical property data of PMIA / P5-n

[0096]

[0097] From Figure 11From Table 6, it can be seen that the pure PMIA has no light transmission below 350 nm, the transmission rate of light in the 800 nm light region is 84.2%, and the transmission rate of light in the 500 nm light region is 74.4%. The cut-off wavelength of the copolyamide PMIA / PA5-n film is in the range of 420.5-425.5 nm, the transmission rate of light with a wavelength of 800 nm is 85-87.4%, and even the transmission rate of light with a wavelength of 500 nm can be maintained at 68.1-82.9%, which indicates that the introduction of the 9-phenoxy-10-phenyl anthracene structure can improve the light transmission rate of the film and increase with the increase of the content of the structure in the molecular chain, indicating that the modified copolyamide film has excellent transparency; combined with the test results of other properties, it also indicates that the modified copolymer has potential application value in the field of organic optoelectronic devices. This is because, on the one hand, the introduction of the third monomer for modification destroys the regularity of the molecular chain, the crystallinity of the copolyamide is reduced, and the transparency is improved; on the other hand, the twisted, non-planar 9-phenoxy-10-phenyl anthracene structure is an asymmetric structure containing an ether bond, which increases the molecular chain spacing and makes the molecular structure more loose, and the polyamide film exhibits high light transmission. However, when the content of the structure is 20%, the film λ0 increases from 350 nm to 420 nm, and with the increase of the content of the PA5 chain segment, λ0 remains basically unchanged in the range of 420.5-425.5 nm, mainly because the PA5 chain segment structure contains a conjugated anthracene group, which increases the charge transfer effect of the molecular chain, so that the PMIA / PA5-20 film has no light transmission below 420 nm.

[0098] Table 6 PMIA / PA5-n film light transmission rate data at different wavelengths

[0099]

[0100] From Table 7 and Figure 12It can be seen that the saturated water absorption of pure PMIA is 4.96%, and the contact angle is 91.9°; the saturated water absorption of copolyamide PMIA / PA5-n is in the range of 3.18-3.59%, and the contact angle is 85.9-92.4°. With the increase of the content of asymmetric structure, the saturated water absorption of copolyamide PMIA / PA5-n shows a downward trend as a whole, and when the content is 30%, the copolyamide has the lowest saturated water absorption of 3.18%, and when the content increases to 80%, the water absorption is still less than that of PMIA. This is because the introduction of asymmetric structure effectively reduces the density of hydrophilic amide bond in the molecular chain of PMIA, making it difficult for water molecules to associate with the molecular chain, and the saturated water absorption of the copolyamide decreases. The contact angle of the copolyamide first increases and then decreases with the increase of the content of PA5 chain segment, and when the content of PA5 chain segment increases to 30%, the copolyamide has the maximum contact angle of 92.4°, and then the contact angle of the copolyamide gradually decreases with the increase of the content of PA5 chain segment, and when the content of PA5 chain segment is 80%, the copolyamide has the minimum contact angle of 85.9°. This is because when the content of PA5 chain segment is less than 30%, the pure PMIA molecular chain lacks polar groups and the density of hydrophilic amide bond in the copolyamide molecular chain is reduced, resulting in the increase of the hydrophobicity of the polymer; when the content of PA5 chain segment is greater than 30%, the content of polar ether bond in the molecular chain structure increases to a greater extent than the decrease of the density of amide bond, which shows that the contact angle of the polymer gradually decreases, and PMIA / PA5-n shows hydrophilicity. In summary, the modified copolyamide PMIA / PA5-n film has better surface wettability, which is beneficial to the entry of dye molecules into the film structure.

[0101] Table 7 Saturated water absorption and contact angle data of PMIA / PA5-n films

[0102]

[0103]

[0104] In summary, PMIA / PA5-n has good solubility, thermal properties, mechanical properties, transparency and hydrophilicity. Compared with pure PMIA, the introduction of 9-phenoxy-10-phenylanthracene structure can improve the heat resistance (T 5％ by 63℃), the flexibility (E b by 15.5%), the light transmittance (T 500nm by 8.3%), and the hydrophilicity (CA decreases by 6°). In terms of comprehensive performance, PA-60 has the best performance, while maintaining a high tensile strength (84.57 MPa), E b increases by 12.8%, and the flexibility of the polymer is greatly improved; T 5％ increases by 50.8℃, and T gAn increase of 20.7°C, in terms of the magnitude of the change in both, increases the processability of the polymer; the transparency of the film (T 500nm 7.8%) and the hydrophilicity is enhanced (CA decreases by 5.3°).

Claims

1. A 9-phenoxy-10-phenylanthracene structure-modified PMIA, characterized by: It has the following molecular structure: Among them, n / (n+m)=0.20~0.

80.

2. The 9-phenoxy-10-phenylanthracene structure-modified PMIA according to claim 1, characterized in that: n / (n+m)=0.40~0.

60.

3. The 9-phenoxy-10-phenylanthracene structure-modified PMIA according to claim 1 or 2, characterized in that: The number average molecular weight is 20,000 to 40,000, and the molecular weight distribution index is 1.0 to 2.

0.

4. The method for preparing a 9-phenoxy-10-phenylanthracene structure-modified PMIA according to claim 1 or 2, characterized in that: 9-(4-carboxyphenoxy)-10-(4-carboxyphenyl)anthracene, isophthalic acid and m-phenylenediamine are polymerized by the Yamazaki phosphonolysis method to obtain the product.

5. The method for preparing 9-phenoxy-10-phenylanthracene structure-modified PMIA according to claim 4, characterized in that: The molar percentage of the 9-(4-carboxyphenoxy)-10-(4-carboxyphenyl)anthracene and isophthalic acid is 20-80%:20-80%; The total molar amount of the 9-(4-carboxyphenoxy)-10-(4-carboxyphenyl)anthracene and isophthalic acid is equal to that of m-phenylenediamine.

6. The method for preparing 9-phenoxy-10-phenylanthracene structure-modified PMIA according to claim 5, characterized in that: The molar percentage composition of the 9-(4-carboxyphenoxy)-10-(4-carboxyphenyl)anthracene and isophthalic acid is 40-60%:40-60%.

7. The method for preparing a 9-phenoxy-10-phenylanthracene structure-modified PMIA according to any one of claims 4 to 6, characterized in that: The polymerization reaction conditions are as follows: firstly heating the temperature to 75-85° C., then slowly heating the temperature to 115-125° C. within 2.5-3.5 hours, and then keeping the temperature for reaction for 4-8 hours.

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