Method for improving hydrophilicity of PEKK chromatographic column screen plate by surface treatment and modified screen plate

Abstract

The application discloses a method for improving the hydrophilicity of a PEKK chromatographic column screen plate by surface treatment and a modified screen plate thereof, relates to the technical field of PEKK chromatographic column screen plates, and comprises a screen plate, wherein the base material of the screen plate is polyether ketone ketone (PEKK) containing a diketone group (-CO-CO-) in the molecular structure. The application realizes efficient and directional surface modification by precisely utilizing the unique diketone group of PEKK as an advantageous modification site through a series of structures. The strong anchoring effect of the diketone group makes the formed hydrophilic layer combined with the base material exceptionally firmly, and significantly improves the durability of the coating. Compared with a traditional PEEK screen plate, the product can effectively inhibit bubble generation and retention in a high-aqueous-phase mobile phase, thereby ensuring stable system pressure and obtaining a smooth baseline, and finally greatly improving the reproducibility, sensitivity and column efficiency of chromatographic analysis.

Description

Technical Field

[0001] This invention relates to the field of PEKK chromatographic column sieve plate technology, specifically to a method for improving the hydrophilicity of PEKK chromatographic column sieve plates through surface treatment and a modified sieve plate thereof. Background Technology

[0002] Column frits are key components in liquid chromatography systems, located at both ends of the column. Their function is to fix the chromatographic packing material while allowing the mobile phase to pass through uniformly. An ideal frit requires excellent chemical inertness, good mechanical strength, precise pore size control, and good compatibility with its packing material and mobile phase. For fields such as reversed-phase chromatography, hydrophilic interaction chromatography (HILIC), and the separation of biomolecules, which widely use aqueous or high-water-proportion mobile phases, the surface hydrophilicity of the frit is crucial. Hydrophobic frit surfaces easily trap air bubbles, leading to unstable column pressure, increased baseline noise, and decreased column efficiency. Polyetheretherketone (PEEK), due to its excellent chemical stability and mechanical properties, has been widely used in the preparation of chromatographic connecting tubing and frits.

[0003] However, PEEK itself is a hydrophobic material (the water contact angle is typically greater than 80°), which limits its performance in hydrophilic applications. Polyetherketoneketone (PEKK), as a homologue of PEEK, not only retains excellent physicochemical properties, but its regularly distributed "diketone" (-CO-CO-) structure in its molecular chain has a higher electron cloud density and reactivity compared to the monoetherketone (-O-CO-) structure of PEEK, providing unique sites for surface chemical modification.

[0004] Polyether ketone ketone (PEKK) is a homologue of PEEK, also possessing excellent mechanical strength, chemical stability, and high-temperature resistance. More importantly, the PEKK molecular chain contains a unique structural unit not found in PEEK: a "diketone" (-CO-CO-) unit composed of two directly linked carbonyl groups. This unique structural feature endows PEKK with higher polarity and a higher density of chemically reactive sites. Theoretical analysis and preliminary experiments show that the diketone group is more likely to generate active sites under plasma irradiation, serving as a stronger anchoring site in chemical grafting reactions and activating adjacent aromatic rings in sulfonation reactions. However, existing technologies, designed for the specific application of chromatographic sieve plates requiring high strength, solvent resistance, and durable hydrophilicity, have not been optimized for chromatographic sieve plates, resulting in insufficient durability of hydrophilicity in modified PEKK chromatographic column sieve plates. Summary of the Invention

[0005] The purpose of this invention is to provide a method for improving the hydrophilicity of PEKK chromatographic column sieve plates using surface treatment and a modified sieve plate thereof, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a modified sieve plate for improving the hydrophilicity of a PEKK chromatographic column sieve plate through surface treatment, comprising a sieve plate, wherein the matrix material of the sieve plate contains polyether ketone ketone (PEKK) with diketone groups in its molecular structure; the surface water contact angle is less than 45°; the sieve plate has a pore size of 1.0-5.0 μm, a porosity of 40%-60%, and a thickness of 1.0-3.0 mm.

[0007] A method for improving the hydrophilicity of PEKK chromatographic column sieve plates using surface treatment, specifically including hydrophilic modification treatment, wherein the surface of the sieve plate is hydrophilic modified with the diketone group as the key activation site to form a stable hydrophilic surface layer.

[0008] Preferably, the hydrophilic modification treatment is an oxygen plasma activation treatment with a treatment power of 80-150W and a treatment time of 10-20min; the treatment atmosphere is oxygen or a mixture of oxygen and an inert gas.

[0009] Preferably, the hydrophilic modification treatment is a surface grafting of a hydrophilic polymer coating, wherein the hydrophilic polymer is selected from at least one of polyethylene glycol, polyvinylpyrrolidone, or poly(meth)acrylate; the coating has a thickness of 0.2-0.8 μm and is covalently bonded to the matrix through sites generated by the activation of the diketone groups.

[0010] Preferably, the oxygen plasma activation treatment includes the following steps: S1 provides a PEKK sieve plate substrate containing a diketone structure and performs surface cleaning; S2 The cleaned substrate is placed in an oxygen plasma device and surface activation is performed in an oxygen-containing atmosphere. The processing power is 80-150W and the processing time is 10-20min. The high reactivity of the diketone group is used to promote the generation of active free radicals on the surface and convert them into oxygen-containing polar groups of hydroxyl and carboxyl groups. S3 performs post-processing on the activated sieve plate to obtain the hydrophilic modified PEKK chromatographic column sieve plate.

[0011] Preferably, the treatment method for the surface grafted hydrophilic polymer coating includes the following steps: S4 provides a PEKK sieve plate substrate containing a diketone structure and performs surface cleaning; S5 performs surface activation pretreatment on the cleaned substrate; S6 involves contacting the pretreated substrate with a solution containing a hydrophilic polymer or its active derivative, chemically grafting the hydrophilic polymer onto the diketone activation sites and the active groups generated during the pretreatment, followed by a curing reaction. S7 was used to clean and dry the material to obtain the hydrophilic modified PEKK chromatographic column sieve plate.

[0012] Preferably, in steps S3 and S7, the sieve plate needs to be sulfonated to introduce sulfonic acid groups onto the surface of the sieve plate; the sulfonation reaction uses sulfuric acid with a concentration of 95%-98% as a reagent, the reaction temperature is 25-40℃, and the reaction time is 20-45min.

[0013] Preferably, the sulfonation reaction includes the following steps: S8 provides a PEKK sieve plate substrate containing a diketone structure and performs surface cleaning; S9 involves immersing the cleaned substrate in a sulfonating agent and reacting it at 25-40°C for 20-45 minutes. The electronic effect of the diketone group is used to activate the adjacent benzene ring, promoting the selective introduction of sulfonic acid groups. S10 removes the substrate, which is then neutralized, thoroughly cleaned, and dried to obtain the hydrophilic modified PEKK chromatographic column sieve plate.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention utilizes a surface treatment method to improve the hydrophilicity of PEKK chromatographic column sieve plates and its modified sieve plates. It distinguishes and utilizes the unique diketone groups in PEKK as "dominant sites" for the modification reaction, making the surface modification process more directional and efficient. This overcomes the shortcomings of traditional methods in modifying materials such as PEEK, such as insufficient site activity and random reaction.

[0015] This paper presents a method for improving the hydrophilicity of PEKK chromatographic column sieve plates through surface treatment, and the resulting modified sieve plates exhibit exceptionally strong bonding with the PEKK matrix through the strong anchoring effect provided by the diketone groups. Whether it's the hydrophilic layer generated by plasma oxidation, the grafted polymer coating, or the chemically bonded sulfonic acid groups, the bonding is exceptionally robust. Accelerated aging experiments and long-term use tests show that the rate of hydrophilicity degradation is significantly lower than that of PEEK sieve plates treated with the same process.

[0016] This method utilizes surface treatment to improve the hydrophilicity of PEKK chromatographic column sieve plates and its modified sieve plates. When using a mobile phase with a high proportion of aqueous phase, it can fundamentally reduce the generation and retention of bubbles, thereby obtaining extremely stable system pressure and a smooth and flat detection baseline, which greatly improves the reproducibility, sensitivity and column efficiency of the analysis. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the preparation process of the hydrophilic modified PEKK chromatographic column sieve plate of the present invention; Figure 2 SEM images of the surface morphology of various PAEK samples after immersion in SBF for 5 days; Figure 3 The graph shows the relationship between immersion time and mass change of PAEK samples in SBF. Figure 4 The graph shows the pH changes of the solution after PAEK samples were soaked in SBF for different times. Figure 5 The image shows the PAEK sample analysis under FTIR spectroscopy. Figure 6 The XRD pattern of the PAEK sample is shown below. Figure 7 This is a schematic diagram illustrating the application of the modified sieve plate of the present invention in a chromatographic column; Figure 8 This is a schematic diagram of the modified sieve plate of the present invention being used in a chromatographic column. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] like Figures 1 to 8 As shown, a modified sieve plate for improving the hydrophilicity of PEKK chromatographic column sieve plates by surface treatment includes a sieve plate. The matrix material of the sieve plate contains polyether ketone ketone (PEKK) with diketone groups in its molecular structure. The surface water contact angle is less than 45°. The sieve plate has a pore size of 1.0-5.0 μm, a porosity of 40%-60%, and a thickness of 1.0-3.0 mm.

[0021] A method for improving the hydrophilicity of PEKK chromatographic column sieve plates using surface treatment, specifically including hydrophilic modification treatment, wherein the surface of the sieve plate is hydrophilic modified with the diketone group as the key activation site to form a stable hydrophilic surface layer.

[0022] Example 1: Hydrophilic modification of oxygen plasma based on diketone activation This embodiment specifically illustrates how to utilize the properties of diketones to achieve efficient and durable hydrophilic modification of PEKK sieve plates through oxygen plasma treatment.

[0023] 1. Substrate Preparation: Commercial-grade injection-molded sintered PEKK microporous sieve plates were selected (brand: OXPEKK, ensuring a high proportion of terephthaloyl chloride units in its polymer chain to guarantee abundant diketone content). Sieve plate specifications: diameter Φ6.4mm, thickness 1.6mm, nominal pore size 2.0μm, porosity approximately 55%.

[0024] 2. Substrate Cleaning: The sieve plate was sequentially placed in analytical grade acetone and anhydrous ethanol, and ultrasonically cleaned for 20 minutes each time to remove organic contaminants. It was then transferred to ultrapure water for ultrasonic cleaning for 15 minutes. After cleaning, it was thoroughly dried in a 60℃ forced-air drying oven.

[0025] 3. Oxygen Plasma Activation Treatment: A flat-plate plasma treatment device (model: PVA TePla 100) is used. The cleaned and dried sieve plate is placed flat on the sample tray and inserted into the reaction chamber. The chamber is evacuated to a background pressure below 5 × 10⁻² mbar. High-purity oxygen (99.999% purity) is introduced into the chamber at a stable flow rate of 50 sccm, maintaining a working pressure of approximately 0.3 mbar. The RF power supply is turned on, the output power is set to 120 W, and the treatment time is set to 18 minutes to begin plasma treatment. During this process, the active species (such as oxygen atoms and ions) in the high-energy oxygen plasma preferentially act on the high-energy diketone groups and their adjacent regions on the PEKK surface, efficiently generating active free radicals, which rapidly combine with oxygen to generate a large number of stable hydrophilic functional groups such as hydroxyl (-OH) and carboxyl (-COOH) groups in situ.

[0026] Post-processing and storage: After the processing is completed, maintain oxygen flow and vacuum conditions for 5 minutes to allow the surface-active species to stabilize further. Then, slowly purge with high-purity nitrogen to atmospheric pressure. Remove the modified sieve plate and immediately place it in a sealed bag filled with nitrogen to prevent contamination by organic matter in the air, pending performance characterization.

[0027] Performance characterization results: Surface hydrophilicity: The static water contact angle was measured using the pendant drop method (contact angle meter, Krüss DSA25). The contact angle of the unmodified original PEKK sieve plate was 94.5°±2.1°, exhibiting strong hydrophobicity. After the above-mentioned oxygen plasma activation modification, the surface contact angle was significantly reduced to 38.2°±1.8°, and the hydrophilicity was greatly improved.

[0028] Hydrophilic durability: To simulate the long-term aqueous environment in actual use, the modified sieve plate was fixed in a special fixture and placed at room temperature. Ultrapure water was continuously flowed over the surface at a flow rate of 0.2 mL / min for 168 hours (7 days). After the experiment, the sample was removed and dried, and its water contact angle was measured again, with a result of 44.7°±2.5°. Although the hydrophilicity decreased slightly, it still remained at an excellent level, proving that the modification effect is durable.

[0029] Example 2: PEG covalent grafting modification based on diketone activation sites This embodiment demonstrates a method for achieving robust grafting of PEG polymers using diketone-related active sites based on plasma preactivation.

[0030] 1. Substrate preparation and cleaning: Same as steps 1-2 in Example 1.

[0031] 2. Surface activation pretreatment (creating grafting sites): The PEKK sieve plate was pretreated using the same oxygen plasma treatment process as step 3 in Example 1. This step aims to generate abundant oxygen-containing polar groups (hydroxyl, carboxyl, etc.) on the surface. At the same time, the diketone structure may also generate specific active intermediates under the action of plasma, which together provide a high density of anchoring sites for the subsequent grafting reaction.

[0032] 3. Grafting solution preparation: Accurately weigh 2.0 g of methoxy-polyethylene glycol-succinimide carbonate (mPEG-SC, molecular weight 1000 Da) and dissolve it in 100 mL of 0.1 M carbonate buffer solution with a pH of 8.5 to prepare a 2.0 wt% active PEG grafting solution. The succinimide carbonate group at the end of mPEG-SC is a highly reactive group that can react with primary amino or hydroxyl groups.

[0033] 4. Grafting Reaction: The plasma-pretreated sieve plate is rapidly (within 5 minutes) completely immersed in the above PEG grafting solution. The reaction vessel is placed in a constant-temperature shaker at 25°C and the reaction is carried out at 100 rpm for 4 hours. During this process, the active ester groups at the ends of the PEG chains undergo a covalent reaction with the amino groups (possibly from the process or environment) or hydroxyl groups generated during the PEKK surface pretreatment, forming strong amide bonds or carbamate bonds, thereby achieving chemical grafting of PEG onto the surface.

[0034] 5. Post-treatment: After the reaction is complete, remove the sieve plate with PTFE tweezers. First, rinse the surface with plenty of ultrapure water, then immerse it in fresh ultrapure water and wash it for 12 hours under low-speed shaking to completely remove any physically adsorbed PEG molecules. Finally, dry it with a stream of clean nitrogen.

[0035] Performance and structural characterization: a. Surface hydrophilicity: After grafting modification, the water contact angle on the sieve plate surface is further reduced to 31.5°±1.5°, showing excellent hydrophilicity.

[0036] b. Solvent Resistance and Stability: PEG-grafted sieve plate samples were immersed in acetonitrile, methanol, tetrahydrofuran, and hydrochloric acid aqueous solution (pH 2.0), respectively, and allowed to stand at a constant temperature of 40℃ for 72 hours. After removal, the samples were washed with ultrapure water and dried, and their water contact angles were measured. The results showed that the contact angle variation of each sample was within ±3°, and scanning electron microscopy (SEM) revealed that the surface coating was intact, without any cracking, wrinkling, or peeling, proving that the coating adhesion was extremely strong.

[0037] c. Surface chemical analysis: X-ray photoelectron spectroscopy (XPS) was used to analyze the surface before and after modification. The atomic ratio of oxygen (O) to carbon (S3) (O / C) on the modified surface was significantly increased. Peak fitting of the C1s spectrum revealed characteristic peaks (binding energy approximately 286.5 eV) belonging to the COC structure in the PEG chain, directly confirming that the PEG polymer was successfully covalently grafted onto the PEKK surface.

[0038] Example 3: Mild sulfonation modification based on diketone activation effect This embodiment demonstrates how to achieve efficient sulfonation of the PEKK surface under relatively mild conditions by utilizing the activation effect of the diketone group on the adjacent aromatic ring.

[0039] 1. Substrate preparation and cleaning: Same as steps 1-2 in Example 1.

[0040] 2. Sulfonation Reaction: In a sealed reaction vessel lined with polytetrafluoroethylene (PTFE), add sufficient 95% (mass fraction) concentrated sulfuric acid as the sulfonating agent. Completely immerse the cleaned and thoroughly dried PEKK sieve plate in the acid solution. Seal the container and place it in a constant temperature water bath at 35°C, stirring magnetically for 30 minutes. The diketone group in the PEKK molecule has an electron-withdrawing effect, effectively activating the adjacent benzene ring and making it more susceptible to electrophilic substitution reactions. This allows for the selective introduction of sulfonic acid groups (-SO3H) under relatively mild conditions (lower acid concentration, lower temperature).

[0041] 3. Reaction Termination and Cleaning: After the reaction is complete, use a PTFE tool to quickly transfer the sieve plate to a beaker containing a large amount of ice-water mixture (0-5℃), and stir slowly to rapidly dilute and cool, quenching the reaction. Then, rinse the sieve plate under running ultrapure water for at least 30 minutes. Next, immerse the sieve plate in a 1 wt% sodium bicarbonate aqueous solution for 30 minutes to neutralize any remaining trace amounts of acid. Finally, rinse repeatedly with ultrapure water until the effluent is neutral (pH≈7).

[0042] 4. Drying: Place the cleaned sieve plate in a vacuum drying oven at 70℃ and dry overnight.

[0043] Performance and structural characterization: Surface hydrophilicity: The sulfonated modified sieve plate surface exhibits extremely strong hydrophilicity. Water droplets spread and are absorbed rapidly on the surface. It is difficult to measure accurately using the conventional pendant drop method. The apparent contact angle is less than 10°, and the measured value is about 8.5°±1.2° (rapid photography is required).

[0044] Surface chemical analysis: XPS analysis showed that sulfur (S) was clearly detected in the broad scan spectrum of the modified sample. High-resolution scanning of the S2p orbitals revealed a distinct characteristic peak at a binding energy of approximately 168.5 eV, corresponding to the sulfur atom in the sulfonic acid group (-SO3H), confirming the successful sulfonation reaction. The density of surface sulfonic acid groups was indirectly estimated to be approximately 0.8 μmol / cm² using methylene blue staining-UV titration.

[0045] Comparative Example 1 (Reference Example): Parallel Control Modification of PEEK Sieve Plates To highlight the advantages of utilizing the PEKK diketone group in this invention, a commercially available pure PEEK sieve plate with identical physical specifications (pore size, porosity, and thickness) to the PEKK sieve plate in Example 1 was selected as a control substrate. The same process parameters and conditions as in Example 1 (oxygen plasma) and Example 3 (sulfonation) were used for treatment.

[0046] Oxygen plasma treatment control: After treatment with the same conditions (120W, O2, 18min), the initial water contact angle of the PEEK sieve plate could be reduced to 52.4°±2.3°. However, after 168 hours of continuous water rinsing as in Example 1, its contact angle rapidly rebounded to 75.8°±3.1°, and the decrease in hydrophilicity was much greater than that of the PEKK sample (from 38.2° to 44.7°).

[0047] Sulfonation treatment control: After treatment under the same sulfonation conditions (95% H2SO4, 35℃, 30min), the initial contact angle of the PEEK sieve plate also decreased to a low level (25.5°±3.0°), but visible swelling and color deepening appeared on the surface. After accelerated water resistance testing (immersion in 80℃ hot water for 48 hours), its contact angle rebounded significantly to over 65°, and numerous fine cracks appeared on the surface under an optical microscope, indicating damage to the material structure. Application Example: Comprehensive Evaluation of Chromatographic Column Performance The modified PEKK sieve plate prepared in Example 1 (labeled PEKK-O2), the PEEK sieve plate treated with oxygen plasma in Comparative Example 1 (labeled PEEK-O2), and the unmodified original PEKK sieve plate were used as inlet end sieve plates and respectively assembled onto three brand-new C18 reversed-phase chromatography columns (specifications: 4.6 mm inner diameter × 150 mm length, packing material: 5 μm C18 silica gel) with identical other conditions.

[0048] Chromatographic test conditions: Mobile phase: 95% ultrapure water / 5% acetonitrile (volume ratio); Flow rate: 1.0 mL / min; Column temperature: 30℃; Detector: Ultraviolet detector, wavelength 214nm; Record the initial pressure after the system has been balanced for 30 minutes, and continuously monitor the system pressure changes over 12 hours of operation.

[0049] Test Results and Analysis: Columns equipped with unmodified PEKK sieve plates: The initial back pressure of the system is high, and the pressure fluctuates drastically during operation (fluctuation range of approximately ±0.5 MPa). The detection baseline is rough and full of burrs. This is a typical manifestation of the continuous generation and collapse of bubbles caused by the hydrophobicity of the sieve plate surface.

[0050] The chromatographic column equipped with the PEEK-O2 sieve plate of Comparative Example 1: The initial system pressure was stable, indicating short-term effectiveness of hydrophilicity. However, after running continuously for about 5 hours, the system pressure began to show obvious periodic small fluctuations (fluctuation range of about ±0.15MPa), and the baseline also showed slight disturbances, indicating that the surface modification layer began to partially fail under long-term scouring by the aqueous phase, and the decrease in hydrophilicity led to the recurrence of the bubble problem.

[0051] The chromatographic column assembled with the PEKK-O2 sieve plate in Example 1 exhibited extremely stable back pressure throughout the entire 12-hour testing period, with fluctuations within ±0.05 MPa, and a smooth, flat detection baseline. This indicates that the hydrophilic modified layer based on diketone activation maintains stable performance under long-term high-aqueous conditions, effectively eliminating bubble interference. Furthermore, when column efficiency was calculated using uracil as the test solute, the column efficiency using the sieve plate of this invention was approximately 12% higher than that using the unmodified sieve plate.

[0052] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A modified sieve plate for improving the hydrophilicity of a PEKK chromatographic column sieve plate through surface treatment, comprising a sieve plate, characterized in that: The matrix material of the sieve plate contains polyether ketone ketone (PEKK) with diketone groups in its molecular structure; the surface water contact angle is less than 45°; the sieve plate has a pore size of 1.0-5.0 μm, a porosity of 40%-60%, and a thickness of 1.0-3.0 mm.

2. The method for improving the hydrophilicity of PEKK chromatographic column sieve plates by surface treatment according to claim 1, characterized in that: The specific method includes hydrophilic modification treatment, in which the surface of the sieve plate is hydrophilic modified with the diketone group as the key activation site to form a stable hydrophilic surface layer.

3. The method for improving the hydrophilicity of PEKK chromatographic column sieve plates by surface treatment according to claim 2, characterized in that: The hydrophilic modification treatment is an oxygen plasma activation treatment with a treatment power of 80-150W and a treatment time of 10-20min; the treatment atmosphere is oxygen.

4. The method for improving the hydrophilicity of PEKK chromatographic column sieve plates by surface treatment according to claim 2, characterized in that: The hydrophilic modification treatment is a surface grafting of a hydrophilic polymer coating, wherein the hydrophilic polymer is selected from at least one of polyethylene glycol, polyvinylpyrrolidone, or polyhydroxyethyl methacrylate; the coating thickness is 0.2-0.8 μm, and the coating is covalently bonded to the matrix through the sites generated by the activation of the diketone groups.

5. The method for improving the hydrophilicity of PEKK chromatographic column sieve plates by surface treatment according to claim 3, characterized in that: The oxygen plasma activation treatment method includes the following steps: S1 provides a PEKK sieve plate substrate containing a diketone structure and performs surface cleaning; S2 The cleaned substrate is placed in an oxygen plasma device and surface activation is performed in an oxygen-containing atmosphere. The processing power is 80-150W and the processing time is 10-20min. The high reactivity of the diketone group is used to promote the generation of active free radicals on the surface and convert them into oxygen-containing polar groups of hydroxyl and carboxyl groups. S3 performs post-processing on the activated sieve plate to obtain the hydrophilic modified PEKK chromatographic column sieve plate.

6. The method for improving the hydrophilicity of PEKK chromatographic column sieve plates by surface treatment according to claim 4, characterized in that: The treatment method for the surface grafted hydrophilic polymer coating includes the following steps: S4 provides a PEKK sieve plate substrate containing a diketone structure and performs surface cleaning; S5 performs surface activation pretreatment on the cleaned substrate; S6 involves contacting the pretreated substrate with a solution containing a hydrophilic polymer or its active derivative, chemically grafting the hydrophilic polymer onto the diketone activation sites and the active groups generated during the pretreatment, followed by a curing reaction. S7 was used to clean and dry the material to obtain the hydrophilic modified PEKK chromatographic column sieve plate.

7. A method for improving the hydrophilicity of PEKK chromatographic column sieve plates using surface treatment according to claim 5 or 6, characterized in that: In steps S3 and S7, the sieve plate needs to be sulfonated to introduce sulfonic acid groups onto the surface of the sieve plate. The sulfonation reaction uses sulfuric acid with a concentration of 95%-98% as a reagent, the reaction temperature is 25-40℃, and the reaction time is 20-45 min.

8. The method for improving the hydrophilicity of PEKK chromatographic column sieve plates by surface treatment according to claim 7, characterized in that: The sulfonation reaction includes the following steps: S8 provides a PEKK sieve plate substrate containing a diketone structure and performs surface cleaning; S9 involves immersing the cleaned substrate in a sulfonating agent and reacting it at 25-40°C for 20-45 minutes. The electronic effect of the diketone group is used to activate the adjacent benzene ring, promoting the selective introduction of sulfonic acid groups. S10 removes the substrate, which is then neutralized, thoroughly cleaned, and dried to obtain the hydrophilic modified PEKK chromatographic column sieve plate.

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