Process for the production of a polyetherketoneketone and its use

Abstract

The application discloses a production method of polyether ketone ketone and application thereof, and relates to the technical field of polymer synthesis. The production method of the polyether ketone ketone comprises the following steps: method one: in an inert atmosphere, acyl chloride and diphenyl ether are subjected to polymerization reaction for a period of time in the presence of a Lewis base, a Lewis acid and a reaction solvent, then a fluorine-containing end-capping agent is added and the reaction is continued for 2-5 hours to obtain an end-capped polyether ketone ketone; or method two: in an inert atmosphere, acyl chloride, diphenyl ether and the fluorine-containing end-capping agent are subjected to polymerization reaction in the presence of the Lewis base, the Lewis acid and the reaction solvent to obtain the end-capped polyether ketone ketone. The fluorine-containing end-capping agent is used to end-cap the PEKK, the molecular weight and the molecular weight distribution of the PEKK are effectively controlled, the thermal stability and the chemical inertness of end groups of the PEKK are significantly enhanced, and the hydrophobicity of the PEKK is improved.

Description

Technical Field

[0001] This invention belongs to the field of polymer synthesis technology and relates to a method for producing polyether ketone and its application. Background Technology

[0002] In the 1960s, DuPont reported a method for preparing polyetherketoneketone (PEKK) in nitrobenzene solution using aluminum trichloride as a catalyst and diphenyl ether and terephthaloyl chloride as monomers. Currently, the electrophilic substitution method for PEKK preparation largely follows or modifies the Lewis acid-Lewis base co-catalytic method invented by Raychem. This method uses dichloromethane as a solvent, adding diphenyl ether, acyl chloride, Lewis base, and Lewis acid at low temperature, followed by heating. Under the co-catalysis of the Lewis base and Lewis acid, PEKK can be prepared at room temperature. As the synthesis route of polyetherketoneketone has matured, its market share in commercial products has gradually increased. For example, manufacturers such as Arkema (France) and Shandong Kaisheng New Materials have launched commercial PEKK products. However, pure PEKK products cannot meet the diverse needs of customers, requiring physical or chemical modification of PEKK. Common modification methods include: 1) Blending, with common blending components such as carbon fiber, glass fiber, PTFE, and graphene. This method is simple, low-cost, and effective, and has become the mainstream modification method. However, it is difficult to achieve nanoscale blending between PEKK and other polymers and inorganic particles, resulting in uneven local distribution. Furthermore, the compatibility between fibers and polymers is poor, and interface defects affect mechanical properties. 2) Copolymerization, including chemical grafting and copolymerization with amide monomers. This method can significantly change polymer properties. Since the components are linked by chemical bonds, it is superior to blending systems in terms of size uniformity and is less prone to phase separation during use. However, the disadvantages are high cost and the different activities of each component during copolymerization, leading to the formation of microblock structures and poor batch stability. 3) Chemical treatment, such as sulfonation, nitration, and plasma treatment. These steps are cumbersome and costly, making them unsuitable for large-scale production. 4) Functional group capping, such as amino, carboxyl, and fluorine groups. This method is low-cost and simple, and has received increasing attention.

[0003] However, existing functional group-capping systems still have certain limitations: some capping agents lack sufficient reactivity, which may lead to a low capping rate, resulting in residual active groups at the ends, thus affecting the stability of the polymer under high-temperature processing conditions; secondly, the content of functional groups in existing capping agents (such as those containing amino and carboxyl groups) is usually low, which limits the modification effect on the polymer system. For example, literature CN110317322B uses aromatic compounds containing protected amine groups (such as 2,2,2-trifluoro-N-(4-phenoxyphenyl)acetamide, N-acetyl-4-phenoxyaniline) as capping agents. Although such capping agents can avoid the reaction of amine groups with acyl chloride monomers during polymerization to form unstable amide bonds, the post-treatment conditions for removing the protecting groups are stringent, and even small fluctuations may lead to incomplete removal of the protecting groups, thereby reducing the free amine content of the polymer end groups and affecting the amine functionalization effect; literature CN114933 Literature 694A explicitly discloses that end-capping agents such as benzoyl chloride, 4-phenoxybenzophenone, and benzenesulfonyl chloride can control polymer chain growth and adjust molecular weight. However, it does not focus on the impact of end-capping agent molecular structure design on the chemical corrosion resistance, low surface energy, and anti-adhesion properties of PEKK, resulting in a limitation in the functional diversity of PEKK materials and making it difficult to meet the application requirements of more specific scenarios. In literature CN118725260A, the end-capping function is achieved in two steps: first, the short chain length is adjusted using diphenyl ether, and then a special end-capping agent is used to complete the final end-capping. However, because the amount of diphenyl ether is strictly limited to a ratio similar to that of acyl chloride, although this method can prevent the short chain from becoming too long, it also results in a limited effect of diphenyl ether on chain length adjustment, remaining only at a preliminary stage. Some active ends are therefore not effectively end-capped, thus failing to eliminate the potential impact of unendaged ends on the long-term stability of PEKK materials. Therefore, developing novel end-capping agents to optimize end-capping efficiency and effectively modifying the system has become one of the research focuses in this field. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0005] A method for producing polyetherketoneketone, the method comprising:

[0006] Method 1: In an inert atmosphere, acyl chloride and diphenyl ether are polymerized in the presence of Lewis base, Lewis acid and reaction solvent for a period of time. Then, a fluorine-containing end-capping agent is added and the reaction is continued for 2-5 hours to obtain end-capped polyether ketone ketone.

[0007] or

[0008] Method 2: In an inert atmosphere, acyl chloride, diphenyl ether, and fluorinated end-capping agent are polymerized in the presence of Lewis base, Lewis acid, and reaction solvent to obtain end-capped polyether ketone ketone.

[0009] According to an embodiment of the present invention, in method one, the number average molecular weight of the obtained end-capped polyether ketone is greater than 23,000 (e.g., 24,000, 25,000, 26,000, 27,000, 28,000, 29,000, 30,000, 35,000, 40,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000, 85,000, 90,000, 95,000, 100,000 or any two of the above). The weight-average molecular weight is greater than 100,000 (e.g., 110,000, 120,000, 130,000, 140,000, 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, 1000,000 or any two of the above values).

[0010] The inventors discovered that in Method 1, adding the fluorinated end-capping agent after a certain period of time during the reaction can yield end-capped polyether ketones with higher molecular weights. Preferably, the timing of adding the fluorinated end-capping agent can be adjusted according to the desired molecular weight of the polyether ketone, and it can be added at any time during the polymerization reaction.

[0011] According to an embodiment of the present invention, in method two, the number average molecular weight of the obtained end-capped polyether ketone is less than 23,000 (e.g., 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 15,000, 20,000 or any two of the above values), and the weight average molecular weight is less than 100,000 (e.g., 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000 or any two of the above values).

[0012] According to an embodiment of the present invention, the fluorinated end-capping agent is selected from fluorobenzoyl chloride compounds and fluorobenzenesulfonyl chloride compounds.

[0013] Preferably, the molecular formula of the fluorobenzoyl chloride compound is F. n -ph-CO-Cl, where n is selected from 2-5, for example, 2, 3, 4. Exemplarily, the fluorobenzoyl chloride compound is selected from at least one of pentafluorobenzoyl chloride, 2,5-difluorobenzoyl chloride, and 2,4,5-trifluorobenzoyl chloride.

[0014] Preferably, the molecular formula of the fluorobenzenesulfonyl chloride compound is F. n -ph-SO2-Cl, where n is selected from 2-5, for example, 2, 3, 4. Exemplarily, the fluorobenzenesulfonyl chloride compound is selected from pentafluorobenzenesulfonyl chloride.

[0015] According to a preferred embodiment of the present invention, the fluorinated end-capping agent is selected from fluorobenzoyl chloride compounds, preferably pentafluorobenzoyl chloride.

[0016] According to an embodiment of the present invention, the acyl chloride is selected from at least one or a mixture of two or more of terephthaloyl chloride, phthaloyl chloride, and isophthaloyl chloride.

[0017] According to an embodiment of the present invention, the Lewis base is selected from at least one of N,N-dimethylformamide, dimethylacetamide, diphenyl sulfone, triphenylphosphine oxide, nitropropane, sulfolane, dimethyl sulfoxide, dimethyl sulfone, N-methylpyrrolidone, anhydrous lithium chloride, and anhydrous sodium chloride, preferably N,N-dimethylformamide.

[0018] According to an embodiment of the present invention, the Lewis acid is selected from at least one of anhydrous aluminum trichloride, anhydrous ferric trichloride, boron trifluoride, anhydrous zinc dichloride, anhydrous antimony pentachloride, and anhydrous tin dichloride, preferably anhydrous aluminum trichloride.

[0019] According to an embodiment of the present invention, the solvent is selected from at least one of dichloromethane, dichloroethane, and o-dichlorobenzene, preferably dichloroethane.

[0020] According to an embodiment of the present invention, the molar ratio of the diphenyl ether to the acyl chloride is 0.8:1 to 1.2:1, preferably 1:1.

[0021] According to an embodiment of the present invention, the molar ratio of the fluorinated capping agent to the acyl chloride is 1:10 to 1:40, preferably 1:25.

[0022] According to an embodiment of the present invention, the mass ratio of the solvent to the acyl chloride is 2:1 to 15:1, preferably 10:1.

[0023] According to an embodiment of the present invention, the molar ratio of the Lewis base to the acyl chloride is 1.5:1 to 3.0:1, preferably 2.5:1.

[0024] According to an embodiment of the present invention, the amount of the Lewis acid, in molar terms, is in the ratio of the total molar of the acyl chloride and the Lewis base to 1.2:1 to 2.0:1, preferably 1.5:1.

[0025] According to an embodiment of the present invention, the polymerization reaction time is 1 to 5 hours, for example, 2 hours, 3 hours, or 4 hours.

[0026] According to an embodiment of the present invention, the temperature of the polymerization reaction is not higher than 25°C, preferably -50°C, -40°C, -30°C, -20°C, -10°C, 0°C, 10°C, or 20°C, for example -20°C.

[0027] According to an embodiment of the present invention, in method one, after the reaction with the addition of the fluorinated end-capping agent is completed, acid is added to the reaction system to decomplex, and the mixture is allowed to stand to obtain a gel-like polymer, which is then post-treated to obtain end-capped polyether ketone ketone.

[0028] According to an embodiment of the present invention, in method two, after the polymerization reaction is completed, acid is added to the reaction system to decomplex the polymer, and the mixture is allowed to stand to obtain a gel-like polymer, which is then post-treated to obtain end-capped polyether ketone ketone.

[0029] According to an embodiment of the present invention, the acid solution is selected from inorganic acids known in the art, such as dilute hydrochloric acid.

[0030] According to an embodiment of the present invention, the settling time is 4 to 10 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, or 9 hours.

[0031] According to an embodiment of the invention, the post-processing includes separating the gelatinous polymer, and optionally further pulverizing and / or washing after separation. Preferably, the separation, pulverizing, and washing can be performed using methods known in the art. Exemplarily, pulverizing includes grinding and sieving. Exemplarily, washing includes washing with deionized water, methanol, and hydrochloric acid, respectively.

[0032] The present invention also provides polyetherketone obtained by the above production method.

[0033] According to an embodiment of the present invention, the end group of the polyether ketone includes the element F.

[0034] According to an embodiment of the present invention, the content of element F in the polyether ketone is greater than 2000 ppm, for example, 2500 ppm, 3000 ppm, 4000 ppm, 5000 ppm, 6000 ppm, 7000 ppm, 8000 ppm, or 9000 ppm.

[0035] According to an embodiment of the present invention, the polydispersity index (PDI) of the polyether ketone is not greater than 5, for example, 3, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, or 4.9.

[0036] According to an embodiment of the present invention, the water absorption rate of the polyether ketone is not greater than 0.06%, for example, 0.05%, 0.04%, 0.03%, 0.02%, 0.01%, or any two of the above values.

[0037] According to an embodiment of the present invention, the number average molecular weight of the polyether ketone is selected from 5,000-100,000, for example 25,000-100,000, or 5,000-25,000; the weight average molecular weight of the polyether ketone is selected from 120,000-1,000,000, or 30,000-120,000.

[0038] According to an embodiment of the present invention, the polyetherketoneketone has chemical corrosion resistance, high temperature oxidation resistance, hydrophobicity, antifouling or anti-adhesion properties.

[0039] The inventors discovered that the polyether ketone ketone (PEKK) prepared by this invention possesses superior chemical corrosion resistance, surface hydrophobicity, and high-temperature stability due to the high electronegativity of fluorine atoms in its end groups and the high bond energy of the CF bonds. When the PEKK polymer chain is capped with a fluorinated end-capping agent, the end of the PEKK polymer chain is protected by an extremely inert perfluoroaryl group, which can effectively resist the erosion of harsh chemical environments. Its low surface energy characteristics give the material surface excellent hydrophobic and oleophobic properties, achieving anti-fouling and anti-adhesion, thereby ensuring the long-term stability of the material's hydrophobicity.

[0040] The present invention also provides the application of the above-mentioned polyether ketone ketone in aerospace, antifouling coatings for the electronics industry, anti-adhesion implants for biomedicine, 3D printing and other fields.

[0041] Beneficial effects

[0042] This invention employs a fluorinated end-capping agent to cap PEKK, effectively controlling the molecular weight and molecular weight distribution of PEKK, significantly enhancing the thermal stability and chemical inertness of the terminal groups, and improving the hydrophobicity of PEKK; the low surface energy characteristics achieved by its fluorinated structure further provide antifouling and anti-adhesion functions, expanding the scope of functional applications of the material. Specifically:

[0043] This invention achieves efficient and precise chain termination using a single fluorinated end-capping agent. The process is simple with few side reactions, significantly improving the reliability of the end-capping process and the controllability of overall performance. The production method of this invention ensures efficient chain termination growth while avoiding raw material waste or residual interference. Furthermore, the fluorinated end-capping agent exhibits good compatibility with preferred reaction systems (such as dichloroethane solvent, anhydrous aluminum trichloride, etc.), and can be uniformly dispersed and react efficiently under low-temperature nitrogen protection. In addition, end-capping agents such as pentafluorobenzoyl chloride are common industrial raw materials, inexpensive, and easy to industrialize.

[0044] The fluorinated end-capping agent of this invention does not require the introduction of a protecting group and can be directly polymerized using commercial raw materials, avoiding complex synthesis and purification steps, simplifying the experimental process, shortening the operation cycle, and being environmentally friendly. It also reduces the risk of introducing impurities due to incomplete purification. During the reaction, pentafluorobenzoyl chloride can be precisely attached to the PEKK chain end through electrophilic substitution, without considering the side reactions of the protecting group with the acyl chloride monomer or Lewis acid. The subsequent decomposition only requires dilute hydrochloric acid, eliminating the deprotection steps of alternating boiling of concentrated hydrochloric acid and ammonia in the prior art, making the post-processing more efficient and environmentally friendly.

[0045] This invention synthesizes fluorinated PEKK using a fluorinated end-capping agent. This end-capping agent has advantages such as high efficiency and low price, and is less expensive than traditional modification methods such as blending and copolymerization. The perfluoroaromatic ring structure in pentafluorobenzoyl chloride, with the strong electronegativity of fluorine atoms and the high bond energy of CF bonds, provides excellent chemical inertness and thermal stability to the polymer chain ends, significantly enhancing its chemical corrosion resistance and high-temperature oxidation resistance. At the same time, the inherent low surface energy of fluorine endows the material with durable hydrophobic, antifouling and anti-adhesion functions. Attached Figure Description

[0046] Figure 1 The infrared spectra are those of Examples 1-5 and Comparative Examples 1-3. Detailed Implementation

[0047] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0048] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0049] Example 1

[0050] Install a thermometer, a stirrer, and a gas delivery tube on a four-necked flask. Place the apparatus in a cryogenic bath and set the temperature to -20°C. Connect the nitrogen flow meter to the nitrogen pipeline, turn on the nitrogen gas, and continuously introduce nitrogen gas through the gas delivery tube to replace the air in the reaction flask for at least 30 minutes, keeping the reaction system dry, and start stirring. Weigh 4.16g pentafluorobenzoyl chloride, 27.6g isophthaloyl chloride, 64g terephthaloyl chloride, 183.2g dichloroethane, 75g Lewis base N,N-dimethylformamide, 76.8g diphenyl ether, and 315g Lewis acid anhydrous aluminum trichloride and add them sequentially to a four-necked flask. Keep the mixture warm for 1 hour, then heat the reaction system to 20°C. After reacting for 4 hours, stop stirring, add dilute hydrochloric acid to decomposite the polymer, and let it stand for 10 hours to obtain a gel-like polymer. Grind, pulverize, and sieve the polymer, and wash it with deionized water, methanol, and hydrochloric acid, respectively, to obtain crude PEKK with pentafluorobenzoyl chloride end caps.

[0051] Example 2

[0052] Install a thermometer, a stirrer, and a gas delivery tube on a four-necked flask. Place the apparatus in a cryogenic bath and set the temperature to -20°C. Connect the nitrogen flow meter to the nitrogen pipeline, turn on the nitrogen gas, and continuously introduce nitrogen gas through the gas delivery tube to replace the air in the reaction flask for at least 30 minutes to remove the air and keep the reaction system dry. Turn on the stirrer. Weigh 27.6g isophthaloyl chloride, 64g terephthaloyl chloride, 183.2g dichloroethane, 75g Lewis base N,N-dimethylformamide, 76.8g diphenyl ether, and 315g Lewis acid anhydrous aluminum trichloride and add them sequentially to a four-necked flask. Keep the temperature for 1 hour. Then heat the reaction system to 20°C and react for 1 hour. Weigh 4.16g pentafluorobenzoyl chloride and add it to the four-necked flask. Continue the reaction for 3 hours, then stop stirring. Add dilute hydrochloric acid to decomposite the polymer and let it stand for 10 hours to obtain a gelatinous polymer. Grind, pulverize, and sieve the polymer. Wash it with deionized water, methanol, and hydrochloric acid respectively to obtain crude pentafluorobenzoyl chloride-terminated PEKK.

[0053] Example 3

[0054] Crude PEKK was prepared according to the method in Example 2, except that: the same molar amount of 2,5-difluorobenzoyl chloride was used instead of pentafluorobenzoyl chloride, and the 2,5-difluorobenzoyl chloride was added after 1 hour of reaction, and stirring was stopped after 3 hours of continued reaction; the other conditions remained unchanged.

[0055] Example 4

[0056] Crude PEKK was prepared according to the method in Example 2, except that: the same molar amount of 2,4,5-trifluorobenzoyl chloride was used instead of pentafluorobenzoyl chloride, and the 2,4,5-trifluorobenzoyl chloride was added after 1 hour of reaction, and stirring was stopped after 3 hours of continued reaction; the other conditions remained unchanged.

[0057] Example 5

[0058] Crude PEKK was prepared according to the method in Example 1, except that pentafluorobenzenesulfonyl chloride was used instead of pentafluorobenzoyl chloride in the same molar amount, while the other conditions remained unchanged.

[0059] Comparative Example 1

[0060] Install a thermometer, stirrer, and gas delivery tube on a four-necked flask. Place the apparatus in a cryogenic constant temperature bath and set the temperature to -20°C. Connect the nitrogen flow meter to the nitrogen pipeline, turn on the nitrogen gas, and continuously introduce nitrogen through the gas delivery tube to purge air from the reaction flask for at least 30 minutes to remove air from the reaction flask and keep the reaction system dry. Turn on the stirrer. Weigh 27.6 g isophthaloyl chloride, 64 g terephthaloyl chloride, 183.2 g dichloroethane, 75 g Lewis base N,N-dimethylformamide, 76.8 g diphenyl ether, and 315 g Lewis acid anhydrous aluminum trichloride and add them sequentially to the four-necked flask. Keep the mixture at this temperature for 1 hour. Then heat the reaction system to 20°C and react for 4 hours. Stop stirring, add dilute hydrochloric acid to decomposite the polymer, and let it stand for 10 hours to obtain a gel-like polymer. Grind, pulverize, and sieve the polymer, and wash it with deionized water, methanol, and hydrochloric acid, respectively, to obtain crude PEKK.

[0061] Comparative Example 2

[0062] Install a thermometer, stirrer, and gas delivery tube on a four-necked flask. Place the apparatus in a cryogenic constant temperature bath and set the temperature to -20°C. Connect the nitrogen flow meter to the nitrogen pipeline, turn on the nitrogen gas, and continuously introduce nitrogen through the gas delivery tube to purge air from the reaction flask for at least 30 minutes to remove air from the reaction flask and keep the reaction system dry. Turn on the stirrer. Weigh 2.53g benzoyl chloride, 27.6g isophthaloyl chloride, 64g terephthaloyl chloride, 183.2g dichloroethane, 75g Lewis base N,N-dimethylformamide, 76.8g diphenyl ether, and 315g Lewis acid anhydrous aluminum trichloride and add them sequentially to the four-necked flask. Keep the mixture at this temperature for 1 hour. Then heat the reaction system to 20°C and react for 4 hours. Stop stirring, add dilute hydrochloric acid to decomposite the polymer, and let it stand for 10 hours to obtain a gelatinous polymer. Grind, pulverize, and sieve the polymer, and wash it with deionized water, methanol, and hydrochloric acid, respectively, to obtain crude PEKK with benzoyl chloride end-capping.

[0063] Comparative Example 3

[0064] Crude PEKK was prepared according to the method in Example 1, except that the same molar amount of p-fluorobenzoyl chloride was used instead of pentafluorobenzoyl chloride, while the other conditions remained unchanged.

[0065] Test Example 1

[0066] Infrared measurements were performed using a Fourier transform infrared spectrometer (model: Thermo Scientific Nicolet iS50). The specific procedures are as follows:

[0067] The polyether ketone powder samples obtained in the above examples and comparative examples were dried and then uniformly mixed with dried potassium bromide at a mass ratio of approximately 1:100. The mixture was then thoroughly ground using an agate mortar until the particle size was less than 2 micrometers to ensure effective transmission of infrared light. Subsequently, it was pressed into transparent sheets with a diameter of 13 mm under a pressure of 10 MPa. Before testing, a blank potassium bromide sheet was used as a background for scanning to eliminate environmental interference. During the formal testing, the spectral resolution was set to 4 cm⁻¹. -1 The scan count was 32 times to optimize the signal-to-noise ratio. A deuterated sulfate triglycine detector was used, covering a wavenumber range of 4000 to 400 cm⁻¹. All tests were conducted at room temperature, and atmospheric water and carbon dioxide interference was automatically subtracted using OMNIC software. Finally, the infrared absorption spectra of each sample in the vibrational frequency region of the characteristic functional groups were obtained, such as... Figure 1 As shown. (Through) Figure 1 The infrared spectrum clearly shows that the PEKK main chain includes carbonyl groups, ether bonds and other structures, and the peak positions and peak heights are similar under different ratios.

[0068] like Figure 1 Comparative Example 1 shows the infrared spectrum of PEKK without F-terminal capping, revealing a region located at approximately 1750 cm⁻¹. -1 The characteristic absorption peak at 1750 cm⁻¹ is attributed to the stretching vibration of the acyl chloride group (-COCl). Therefore, in the unterminated PEKK system, the terminal group of PEKK contains an acyl chloride group, i.e., at 1750 cm⁻¹. -1 There is a characteristic absorption peak at ( Figure 1 (Example 1) Figure 1 As can be seen from Examples 1-5 and Comparative Examples 2 and 3, when the PEKK end group is completely capped by F, the stretching vibration peak of the acyl chloride group (-COCl) will disappear, which can directly prove whether PEKK is effectively capped by F.

[0069] Test Example 2

[0070] (1) The molecular weights of the products obtained in the examples and comparative examples were determined as follows:

[0071] Molecular weight distribution was determined using a high-temperature gel permeation chromatography (TPC) instrument at C0.05. 10 H7Cl was used as the mobile phase, and a PLgel Olexis column with a total length of 650 mm was used for the test.

[0072] The test conditions were as follows: mobile phase refractive index (RI) of 1.631, flow rate of 1 mL / min, temperature of 150 °C, injection volume of 200 μL, sample concentration of 0.1 mg / mL, and a differential refractive index detector (RI).

[0073] The test parameters were set to K=14.1 and α=0.7. A narrow-distribution standard sample was used for calibration, and the calibration curve was a first-order polynomial.

[0074] logM = a + b RT (RT is the retention time, in minutes).

[0075] The coefficients a = 13.07, b = -0.591803, and the linear correlation coefficient is -0.99881. The data were processed using Cirrus 3.4 software.

[0076] Additionally, based on the molecular weight test results, the Z-mean molecular weight (M) was calculated. z The calculation formula is M. z = Σ(Ni·Mi 3 ) / Σ(Ni·Mi 2 ) ;

[0077] Z-average molecular weight (Mz) refers to extremely high molecular weight, which statistically assigns a very high weight to high molecular weight components. Therefore, it is highly sensitive to extremely long-chain molecules or trace amounts of high molecular weight end-products in the system. This parameter can effectively reveal the presence of a small number of ultra-long chain segments in the sample. These segments have a critical impact on the polymer's melt elasticity, tensile properties, and long-term mechanical stability that far exceeds their content ratio.

[0078] (2) The fluorine content in the crude PEKK obtained in the above examples and comparative examples was quantitatively analyzed by inductively coupled plasma (ICP).

[0079] (3) To systematically evaluate the hydrophobic properties of fluorinated end-capped polyether ketone and its improvement on the bulk properties of the material, the present invention conducted the following water absorption rate test:

[0080] Tensile specimens with a thickness of 3.2 mm were prepared from the PEKK crude samples obtained in the above examples and comparative examples, in accordance with ASTM-D638-2022. According to the ISO 62-2008 test method, the specimens were immersed in water at 23±1℃ for 24±1 h. The water on the surface of the specimens was quickly wiped off with a clean dry cloth. The mass change of the tensile specimens before and after immersion was accurately measured as m1-m0, where m1 represents the mass after immersion and m0 represents the mass before immersion. The water absorption rate of the tensile specimens (m1-m0) / m0 was calculated.

[0081] The molecular weight distribution, F element content, and water absorption rate of Examples 1-5 and Comparative Examples 1-3 are shown in Table 1 below:

[0082] Table 1

[0083]

[0084] The inventors discovered that although fluorine-containing groups typically exhibit stretching vibration peaks of CF bonds in infrared spectra, these peaks fall within the range of 1000-1400 cm⁻¹. -1 The region contains fluorine, but this region overlaps with the absorption peaks of functional groups (such as ether bonds and aromatic rings) on the polyether ketone backbone. Furthermore, fluorine only appears at the end groups of the polymer chain and its content is low, making it difficult to identify and quantify the fluorine characteristic peaks independently and clearly. Therefore, to accurately evaluate the effect of F-termining in this invention, it is necessary to combine the changes in the acyl chloride group peaks in the infrared spectrum with the quantitative analysis results of fluorine content by inductively coupled plasma (ICP) for a comprehensive judgment. Specifically:

[0085] like Figure 1 In the infrared spectrum of Example 1, at 1750 cm⁻¹ -1 No characteristic absorption peaks attributable to acyl chloride end groups were observed nearby, indicating that the fluorinated end-capping agent had efficiently completed the end-capping reaction, and the active ends were fully replaced. Similarly, Examples 2-5, Comparative Examples 2 and 3 also showed excellent end-capping effects, with almost no obvious acyl chloride peaks detected in their spectra, further confirming the good reliability and repeatability of this end-capping method. Conversely, in Comparative Example 1, the characteristic peak of the acyl chloride was clearly visible, confirming that a large number of unreacted acyl chloride groups existed at the polymer chain ends without the use of an end-capping agent.

[0086] To further quantitatively evaluate the end-capping efficiency, combined with inductively coupled plasma (ICP) analysis of fluorine content (Table 1), significant fluorine content (range 2820-8911 ppm) was detected in Examples 1-5, while no fluorine was detected in Comparative Examples 1-2, and Comparative Example 3 contained only 1714 ppm (using monofluorine), confirming that fully F-terminated polyetherketoneketone can be obtained when using the fluorinated end-capping agent of this application for polymerization reaction.

[0087] According to the molecular weight test results in Table 1:

[0088] Examples 1 and 2, using pentafluorobenzoyl chloride as the capping agent, exhibited significant advantages compared to Comparative Example 2, which used benzoyl chloride as the capping agent: the number-average molecular weights (Mn) of Examples 1 and 2 were 19775 and 26009, respectively, higher than the Mn (18943) of Comparative Example 2; in terms of weight-average molecular weight (Mw), the Mw of Example 1 (80538) was lower than the Mw (99567) of Comparative Example 2, while the Mw (122693) of Example 2 was higher. Meanwhile, the polydispersity index (PDI) of Examples 1 and 2 were 4.07 and 4.72, respectively, lower than the 5.26 of Comparative Example 2. This indicates that the fluorinated capping agent of the present invention can more effectively control polymer chain growth, resulting in polyetherketoneketones with a narrower molecular weight distribution. Furthermore, by adjusting the timing of the capping agent's addition (as in Example 2), a higher molecular weight can be obtained while maintaining a narrow distribution. Improved molecular weight distribution helps enhance the processing stability of the polymer, while a higher molecular weight is beneficial for improving its mechanical properties.

[0089] The Z-average molecular weight (Mz), number-average molecular weight (Mn), and weight-average molecular weight (Mw) of Example 2 were all higher than those of Example 1, but the PDI was slightly higher. This indicates that adding the end-capping agent after the reaction has been underway for a period of time allows the polymer chains more time to grow before end-capping, resulting in a product with a higher molecular weight. Conversely, adding the end-capping agent at the beginning of the reaction prematurely terminates chain growth, reducing the molecular weight. Therefore, this invention can adjust the molecular weight distribution and size by changing the timing of the end-capping agent addition to meet the performance requirements of polymers in different applications.

[0090] According to the water absorption test results in Table 1:

[0091] The water absorption rate of Comparative Examples 1-3 was 0.07, indicating that the hydrophobicity of the uncapped, fluorine-free capped, or monofluorinated capping agents (Comparative Examples 2 and 3) systems was not improved. In contrast, Examples 1 and 5 had the lowest water absorption rate (0.05), corresponding to the highest fluorine content (8570 and 8911 ppm, respectively). This shows that as the number of fluorine atoms in the capping agent increases, the hydrophobicity of the material increases and the water absorption rate decreases. The water absorption rate of the other examples (2-4) was 0.06, and their fluorine content and chain-terminal fluorine atom data further corroborated the above conclusion.

[0092] Water absorption tests revealed that if uncapped polar end groups (such as acyl chloride groups or carboxyl groups that may be generated by hydrolysis) or hydrophilic structures exist within the polymer, water molecules will be adsorbed and fixed through hydrogen bonding, leading to a significant increase in mass. Fluorine-capped end groups, however, transform these highly reactive hydrophilic ends into chemically inert and highly hydrophobic perfluoroaryl structures, blocking the binding pathway between water molecules and the polymer chain ends, thus reducing the hydrophilicity of PEKK.

[0093] In summary, based on the results of infrared spectroscopy, ICP elemental analysis, and water absorption characterization, it can be seen that the fluorine-terminated PEKK prepared by the method of this invention has a significant effect on improving the hydrophobicity and stability of the material.

[0094] The exemplary embodiments of the present invention have been described above. However, the scope of protection of this application is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing polyetherketoneketone, characterized in that, The production method includes: Method 1: In an inert atmosphere, acyl chloride and diphenyl ether are polymerized in the presence of Lewis base, Lewis acid and reaction solvent for a period of time. Then, a fluorine-containing end-capping agent is added and the reaction continues for 2-5 hours. Acid solution is added to decomposite the polymer, and the mixture is allowed to stand to obtain a gel-like polymer. After post-treatment, the end-capped polyether ketone ketone is obtained. or Method 2: In an inert atmosphere, acyl chloride, diphenyl ether and fluorinated end-capping agent are polymerized in the presence of Lewis base, Lewis acid and reaction solvent. Acid solution is added to decomplex, and the mixture is allowed to stand to obtain a gel-like polymer. After post-treatment, end-capped polyether ketone ketone is obtained. The end groups of the polyether ketone ketone include the element F; the content of the element F in the polyether ketone ketone is greater than 2000 ppm; the polydispersity index of the polyether ketone ketone is not greater than 5; the water absorption rate of the polyether ketone ketone is not greater than 0.06%. The fluorinated end-capping agent is selected from fluorobenzoyl chloride compounds and fluorobenzenesulfonyl chloride compounds; the molecular formula of the fluorobenzoyl chloride compound is F. n -ph-CO-Cl, where n is selected from 2-5; the molecular formula of the fluorobenzenesulfonyl chloride compound is F n -ph-SO2-Cl, where n is selected from 2 to 5; The molar ratio of the diphenyl ether to the acyl chloride is 0.8:1 to 1.2:1; The molar ratio of the fluorinated end-capping agent to the acyl chloride is 1:10 to 1:40; The mass ratio of the solvent to the acyl chloride is 2:1 to 15:1; The molar ratio of the Lewis base to the acyl chloride is 1.5:1 to 3.0:1; The amount of the Lewis acid used, in molar terms, is in the ratio of its molar to the total molar of the acyl chloride and Lewis base, which is 1.2:1 to 2.0:

1.

2. The production method according to claim 1, characterized in that, In Method 1, the number-average molecular weight of the end-capped polyether ketone is greater than 23,000 and the weight-average molecular weight is greater than 100,000. In Method 2, the number-average molecular weight of the resulting capped polyether ketone is less than 23,000, and the weight-average molecular weight is less than 100,000.

3. The production method according to claim 1, characterized in that, The fluorobenzoyl chloride compounds are selected from at least one of pentafluorobenzoyl chloride, 2,5-difluorobenzoyl chloride, and 2,4,5-trifluorobenzoyl chloride.

4. The production method according to claim 1, characterized in that, The fluorobenzenesulfonyl chloride compounds are selected from pentafluorobenzenesulfonyl chloride.

5. The production method according to claim 1, characterized in that, The acyl chloride is selected from at least one or a mixture of two or more of terephthaloyl chloride, phthaloyl chloride, and isophthaloyl chloride.

6. The production method according to claim 1, characterized in that, The Lewis base is selected from at least one of N,N-dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

7. The production method according to claim 1, characterized in that, The Lewis acid is selected from at least one of anhydrous aluminum trichloride, anhydrous ferric trichloride, boron trifluoride, anhydrous zinc dichloride, anhydrous antimony pentachloride, and anhydrous tin dichloride; The solvent is selected from at least one of dichloromethane, dichloroethane, and o-dichlorobenzene.

8. The production method according to claim 1, characterized in that, The polymerization reaction takes 1 to 5 hours; The polymerization reaction temperature is not higher than 25°C.

9. The production method according to claim 1, characterized in that, The settling time is 4 to 10 hours; The post-processing includes separating, crushing, and / or washing the gelatinous polymer.

10. The application of the polyether ketone ketone obtained by the production method according to any one of claims 1-9 in the fields of aerospace, antifouling coatings for the electronics industry, preparation of biomedical anti-adhesion implants, or 3D printing.

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