Temperature-responsive polyether ether ketone separation membrane and preparation method thereof, valve device

Abstract

This invention belongs to the field of polyetheretherketone (PEEK) composite separation membrane technology, specifically relating to a temperature-responsive PEEK separation membrane, its preparation method, and a valve device. The composite separation membrane is prepared using an integrated process of "PEEK chemical modification – CNT multi-stage dispersion – NIPS membrane fabrication – UV grafting," achieving efficient solution processing of PEEK, uniform dispersion of CNTs with a high content (45-50%), and precise grafting of PNIPAm temperature-responsive groups. The membrane exhibits reversible hydrophilic / hydrophobic switching characteristics within the 30-38℃ range, and possesses excellent solvent resistance (linear expansion ≤3% after 12 hours of immersion in chloroform), high mechanical strength, and conductivity. An electrically triggered separation device based on this membrane, through the Joule heating effect of the CNT network within the membrane, can achieve a rapid temperature response of 60-180 s at ≤5 V voltage, with a flux on / off ratio ≥3 and a flux recovery rate ≥90% after 50 cycles. It is suitable for intelligent, efficient, and low-energy separation of oil-in-water / water-in-oil emulsions and immiscible organic liquid mixtures.

Description

Technical Field

[0001] This invention belongs to the field of polyether ether ketone (PEEK) composite separation membrane technology, specifically relating to a temperature-responsive PEEK separation membrane, its preparation method, and a valve device. Background Technology

[0002] With the rapid development of the petroleum and chemical industries, the need for separating oily wastewater and complex organic liquid mixtures is becoming increasingly urgent. Membrane separation technology has become a core solution due to its advantages such as no secondary pollution and low energy consumption; however, existing technologies face the following technical bottlenecks: Traditional organic membranes have poor solvent resistance: conventional membrane materials such as polyvinylidene fluoride (PVDF) and polyphenylene sulfone (PPSU) are prone to swelling or dissolving in strong solvents such as chloroform and tetrahydrofuran, resulting in decreased flux and shortened lifespan, which cannot meet the long-term stable operation requirements of the chemical industry. PEEK (polyether ether ketone) membranes are difficult to process and have limited functions: PEEK has excellent solvent and heat resistance, but it is difficult to dissolve in conventional solvents. Strong acid dissolution can easily destroy its crystal structure, and existing PEEK membranes lack intelligent response capabilities. Poor CNT (carbon nanotube) dispersion in CNT / PEEK composite films: In traditional methods, CNTs tend to agglomerate due to strong van der Waals forces, and high-viscosity PEEK is difficult to fully wet CNTs, resulting in a CNT content generally below 5%, poor dispersion uniformity, and difficulty in achieving synergistic functionalization and enhancement effects. Temperature-responsive membranes have a narrow range of applications: existing temperature-sensitive membranes are mostly limited to oil-water separation, have poor adaptability to immiscible organic systems, and have slow response speeds and high energy consumption. Summary of the Invention

[0003] The purpose of this invention is to provide a temperature-responsive polyether ether ketone (PEEK) separation membrane, its preparation method, and a valve device thereof.

[0004] A first aspect of the present invention provides a method for preparing a temperature-responsive polyetheretherketone (PEEK) separation membrane, comprising: Step 1: Prepare PEEK precursor; Step 2: Prepare PEEK modified powder; Step 3: Prepare a uniform dispersion of CNTs; Step 4: Prepare CNT / PEEK composite casting solution; Step 5: Prepare CNT / PEEK composite porous membrane using the NIPS method; Step 6: Graft temperature-responsive groups by ultraviolet irradiation.

[0005] In one embodiment of this application, the method for preparing the PEEK precursor in step 1 includes: Under a nitrogen atmosphere, PEEK powder was dissolved in a mixed solvent of anhydrous dichloromethane and trifluoroacetic acid, 1,3-propanedithiol and p-toluenesulfonic acid were added, and after stirring, methanol was poured in to precipitate the product. The product was then dried to obtain the PEEK precursor. The molar ratio of 1,3-propanedithiol to PEEK powder was 2:1 to 3:1, preferably 3:1; the molar ratio of p-toluenesulfonic acid to PEEK powder was 0.05:1 to 1:1, preferably 1:1.

[0006] In one embodiment of this application, the method for preparing PEEK modified powder in step 2 includes: dissolving the PEEK precursor in anhydrous dichloromethane, adding 1,2-ethylene glycol and NBS, stirring, pouring in methanol to precipitate the precipitate, washing and drying to obtain PEEK modified powder; wherein The molar ratio of 1,2-ethylene glycol to PEEK precursor is 3:1 to 4:1, preferably 4:1; the molar ratio of NBS to PEEK precursor is 1:1 to 2:1, preferably 1.5:1.

[0007] In one embodiment of this application, the method for preparing a uniform CNT dispersion in step 3 includes: CNT powder, dispersant, and deionized water were mixed and then mechanically stirred and ultrasonically dispersed to obtain a uniform CNT dispersion. The solid-liquid ratio of CNT powder in deionized water is controlled at 0.2~1.0 g / L, preferably 0.5 g / L; the mass ratio of CNT to dispersant is 1:2~1:4, preferably 1:3; The dispersant is Triton X-100 or sodium dodecyl sulfate.

[0008] In one embodiment of this application, the method for preparing the CNT / PEEK composite casting solution in step 4 includes: mixing PEEK modified powder and CNT uniform dispersion at a mass ratio of 1:1, adding ionic liquids [BMIM] BF4, THF, and DMAc, and then mechanically stirring, ultrasonically dispersing, and centrifuging to remove impurities to obtain the composite casting solution; wherein The amount of the ionic liquid [BMIM] BF4 added is 3-12 wt%; The volume ratio of THF to DMAc is 2:1; The total solids content of the composite casting solution is 10-15% w / w; The residual amount of ionic liquid [BMIM] BF4 after extraction and washing is ≤100ppm.

[0009] In one embodiment of this application, step 5, the preparation of the CNT / PEEK composite porous membrane using the NIPS method, includes: After the composite casting solution was coated and placed at room temperature, it was then immersed in a deionized water coagulation bath for curing, resulting in a CNT / PEEK composite porous membrane. The wet film thickness is 150-200μm, and the room temperature storage time is 0.1-0.5 hours; The coagulation bath temperature is 25℃, and the curing time is 4 hours; Soaking time is 24 hours.

[0010] In one embodiment of this application, the method of grafting temperature-responsive groups with ultraviolet irradiation in step 6 includes: The composite porous membrane was immersed in a 3M NIPAm ethanol solution, irradiated with ultraviolet light, and washed to obtain a composite separation membrane.

[0011] In some embodiments, step 7 may be included after step 6, CNT content calculation: Weigh a hydrophilic polytetrafluoroethylene (PTFE) filtration membrane (or nylon or polypropylene filtration membrane, pore size 0.45 μm) as M1; take the remaining uniformly dispersed CNT liquid, vacuum filter it, and place the filtration membrane with CNTs in a vacuum drying oven at 80-150℃ (preferably 120℃) for 4-12 hours (preferably 6 hours), weigh the total mass of CNTs with the filtration membrane after drying as M2; weigh the mass of the CNT / PEEK composite porous membrane peeled off from the glass plate after drying as M3; calculate the CNT content in the final composite separation membrane according to the formula [(M0-M2+M1) / M3]×100%, which is 45-50%.

[0012] A second aspect of the present invention provides a temperature-responsive polyetheretherketone separation membrane, prepared using the preparation method described above.

[0013] In one embodiment of this application, the temperature-responsive polyetheretherketone separation membrane has at least one of the following characteristics: PNIPAm is confined to 0.2-2 μm; CNT content is 20-60 wt%; LCST is 30-38℃; After soaking in chloroform for 12 hours, the linear expansion is ≤3% and the mass swelling is ≤8%. The tensile strength is 30-40% higher than that of pure PEEK film; At 25℃, the water contact angle is ≤25°; at 40℃, the water contact angle is ≥95°. The retention rate is ≥99.5% when separating oil-in-water emulsions.

[0014] A third aspect of the present invention provides a Joule-LCST integrated self-triggering valve device, comprising: The composite separation membrane uses the temperature-responsive polyetheretherketone separation membrane described above, which contains a CNT conductive network and a pore-confining PNIPAm layer. Electrodes electrically connected to the CNT conductive network are disposed on both sides of the composite separation membrane; The power module is connected to the electrodes; An online detection unit is used to detect the temperature of the composite separation membrane; The controller is used to control the power module to apply or turn off the voltage to the CNT conductive network of the composite separation membrane as needed, so as to control the temperature of the composite separation membrane within a preset range.

[0015] A fourth aspect of the present invention provides a method for separating the electrically triggered temperature response of the Joule-LCST integrated self-triggering valve device as described above, comprising the following steps: 1) Separation is performed at room temperature using a hydrophilic / underwater superoleophobic separation mode; 2) When flux needs to be turned on, apply a voltage of ≤5V to the CNT conductive network, control the membrane surface temperature in a closed loop to 38-40℃, and switch to hydrophobic / oleophilic mode; 3) When the flow needs to be shut off, disconnect the power and cool down to ≤30℃ to restore the hydrophilic / underwater superoleophobic mode; 4) When the flux decays to below 80% of its initial value, apply a 5-12V voltage for 3-10s electrothermal pulse, followed by water backflushing to achieve self-cleaning and restore the flux.

[0016] In one embodiment, specifically, the Joule-LCST integrated self-triggering valve device uses a temperature-responsive polyether ether ketone (PEEK) separation membrane as its core. Through the integration of electrodes, power supply, detection, and control units, it achieves electrically triggered temperature response regulation. The specific components are as follows: (1) Core components of the device Composite membrane module: The temperature-responsive polyetheretherketone separation membrane described above is used, which contains a CNT conductive network and a pore-confining PNIPAm layer. After immersion in chloroform for 12 hours, the linear expansion is ≤3% and the mass swelling is ≤8%. Electrode systems: These are divided into in-plane comb-shaped finger electrodes (IDE, finger width / finger spacing 0.2-2.0 mm, covering ≥80% of the effective separation area) or sandwich / clamping electrodes (inert carbon cloth / titanium mesh, sealed with a PTFE frame to form a flow channel); the electrode materials are selected from titanium / ruthenium oxide coating, graphite / carbon cloth, gold or ITO, and are dielectrically isolated from the feed liquid to avoid electrolysis; Power supply unit: Employs a SELV DC constant voltage / constant current source, with an output voltage ≤12V and a current density ≤50mA·cm. -2 It is equipped with overcurrent / overtemperature protection and meets IP54 and above protection and intrinsic safety isolation design in solvent-containing environments; Online detection unit: includes resistance detection (four-wire method to measure R(T), acting as a substitute for temperature signal), temperature sensing (NTC / RTD / FBG, directly measuring membrane edge temperature), and flux / differential pressure detection (secondary criterion). Control unit: Employs PID or PWM pulse control strategy to maintain membrane surface temperature at LCST±1℃ based on detection signal; when membrane fouling occurs, outputs 3-10s electro-thermal pulse to achieve self-cleaning, followed by cooling and reset.

[0017] (2) Working mechanism of the device Applying a low voltage (≤5V) to the CNT conductive network causes the CNT network to act as a miniature electric heater, generating Joule heating and enabling the PNIPAm layer in the aperture region to rapidly cross the LCST. Below LCST (≤30℃): Membrane surface is hydrophilic / underwater superoleophobic (water contact angle ≤25°), low flux (off state); LCST and above (≥38℃): Membrane surface is hydrophobic / oleophilic (water contact angle ≥95°), high flux (on-state); Because the heating element is located in the same position as the functional layer, the heat transfer path is short (time constant 60-180s) and the energy consumption is low (single-cycle energy density ≤0.5-3J·cm). -2 It has minimal impact on the temperature of the liquid.

[0018] The beneficial effects of this invention are: 1. Overcoming the dual bottlenecks of PEEK processing and CNT dispersion-conductivity: A "dichloromethane-trifluoroacetic acid" composite solvent system combined with chemical modification is used to achieve homogeneous dissolution of PEEK, avoiding crystallization damage caused by strong acids. Through a "mechanical stirring + multi-stage ultrasonic" dispersion process, the CNT content reaches 20-50 wt%, which is much higher than <5% of the traditional method, and forms a through conductive network, solving the problems of traditional CNT agglomeration and conductivity failure. 2. Achieve precise temperature response via electrical triggering: "In-situ heating" based on CNT Joule heating replaces external heating, reducing the response time to 60-180 s, with an on / off throughput ratio of ≥3 (25℃ vs 40℃), and a feed temperature disturbance of ≤2℃, making it suitable for heat-sensitive separation scenarios. 3. Multi-performance synergy and functional expansion: The composite membrane exhibits linear expansion of ≤3% and mass swelling of ≤8% after 12 hours of chloroform immersion, with tensile strength 30-40% higher than that of pure PEEK membrane. The device integrates closed-loop control and a 3-10 s electro-thermal self-cleaning function, with a flux recovery rate of ≥90% after ≥50 cycles, meeting the requirements for long-term stable operation. 4. Large-scale and safe / reliable equipment: The electrodes, power supply, and control unit all employ mature technologies (such as roll-to-roll coating film production with a linear speed of 0.2-2.0 m / min). -1It contains no highly toxic reagents, and its SELV power supply and IP54 protection design ensure electrical safety in solvent environments, making it easy for industrial mass production.

[0019] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the Joule-LCST integrated self-triggering valve device in one embodiment; Figure 2 This is a schematic diagram of the cross-sectional structure of a membrane module in one embodiment; Figure 3 This is a schematic diagram of the planar structure of the in-plane finger fork electrode in one embodiment.

[0023] The components in the attached diagram are labeled as follows: 1. Feed tank; 2. Metering pump; 3. Pre-filter; 4. Pressure gauge; 5. Membrane module, 5A inlet, 5B outlet; 6. Power supply; 7. Controller; 8. Sensor; 9. Safety relief valve; 10. Flow meter. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions 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, 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.

[0025] The following are specific examples of preparation. Example 1: Preparation of a temperature-responsive polyetheretherketone (PEEK) separation membrane Step 1, Preparation of PEEK precursor: Following the technical procedure, 9.48 g of PEEK powder was added to a 1000 mL round-bottom flask, and a mixed solvent of 500 mL anhydrous dichloromethane and 49.50 mL trifluoroacetic acid was poured in. The mixture was stirred for 0.5 hours under nitrogen protection until a deep yellow solution was formed. 9.93 mL of 1,3-propanedithiol and 5.64 g of p-toluenesulfonic acid were added, and the mixture was stirred for another hour. The mixture was slowly poured into 800 mL of methanol, and a white precipitate was formed. After filtration, the precipitate was dried at room temperature to obtain 11.86 g of PEEK precursor (yield: 93.6%).

[0026] Step 2, Preparation of PEEK modified powder: Dissolve 6.27g of PEEK precursor in 500mL of anhydrous dichloromethane and stir for 0.1 hours; add 3.68g of 1,2-ethylene glycol and 4.12g of NBS (N-bromosuccinimide), and stir at room temperature for 2 hours; pour the reaction solution into 600mL of methanol, and a white flocculent precipitate will precipitate. Wash with methanol 3 times, dry at room temperature, and obtain 5.10g of PEEK modified powder (yield: 93.0%).

[0027] Step 3, prepare a uniform CNT dispersion: Weigh 0.1g of multi-walled CNT powder (diameter 10-20nm, length 10-20μm) at room temperature and add it to a beaker; add 0.2g of sodium dodecyl sulfate and 400mL of deionized water; mechanically stir at 1000r / min for 1 hour and ultrasonically disperse at 900W for 8 hours to obtain a uniform CNT dispersion.

[0028] Step 4, Preparation of CNT / PEEK composite casting solution: Mix 8.50g of PEEK modified powder with 8.50g of CNT dispersion, add 1.02g of [BMIM] BF4, 31.50mL of THF (tetrahydrofuran) and 15.75mL of DMAc (N,N-dimethylacetamide); mechanically stir at 800 r / min for 1.5 hours, ultrasonically disperse at 600W for 3 hours; centrifuge at 3000 r / min for 10 minutes, and take the supernatant as the composite casting solution.

[0029] Step 5: Preparation of CNT / PEEK composite porous membrane by NIPS method (non-solvent-induced phase separation method): Pour the composite casting solution onto a glass plate, scrape the membrane with a wet thickness of 200 μm, and place it at room temperature for 0, 15, and 30 s respectively (comparative experiment, the three times are time intervals); immerse it in a 25℃ deionized water coagulation bath for 4 hours; after membrane separation, hydrolyze it in deionized water for 1 hour, and then immerse the membrane in formic acid (88%) for 48 hours or in hydrochloric acid (37%) for 24 hours at room temperature, changing the acid every 12 hours; then, rinse the membrane with water and transfer it to a water bath to remove residual solvent and ionic liquid, obtaining CNT / PEEK composite porous membrane.

[0030] Step 6, UV irradiation grafting of temperature-responsive groups: Prepare a 3M (i.e., 3 mol / L) NIPAm (N-isopropylacrylamide) ethanol solution (containing 0.1 wt% p-hydroxyanisole); immerse the composite porous membrane in the solution for 0.5 hours, fix it between two 40W UV lamps (12 cm apart), and irradiate for 8 hours; wash it alternately with deionized water and ethanol 4 times, and store it at 25℃ to obtain the target composite separation membrane.

[0031] Step 7, CNT content calculation: Weigh the PTFE filtration membrane (M1 = 0.19 g); after filtration and drying, the remaining CNT dispersion has a total mass of M2 = 0.23 g; weigh the composite porous membrane (M3 = 0.12 g); calculate the CNT content using the formula [(0.1 - 0.23 + 0.19) / 0.12] × 100% = 50%. This verifies the accuracy of the PEEK and CNT ratio, proving that there is no significant CNT loss and no large amount of ionic liquid residue.

[0032] Example 2: Assembly and performance testing of the "Joule-LCST integrated self-trigger valve" device (1) Assembly of the device Electrode fabrication: In-plane finger electrodes (titanium / ruthenium oxide coating) were fabricated using photolithography, with a finger width of 0.5 mm, a finger spacing of 0.5 mm, and covering 85% of the effective separation area; Membrane module assembly: Assemble in the following order: "end plate - sealing gasket - finger electrode - porous support mesh - CNT / PEEK composite membrane - porous support mesh - finger electrode - sealing gasket - end plate", and fix with bolts to form flow channels (inlet / outlet). Control system setup: Connect the SELV DC power supply (output voltage 0-12V), NTC temperature sensor (accuracy ±0.1℃), flow meter, and PID controller, and set the temperature control point to 35±1℃. The NTC temperature sensor measures the macroscopic temperature of the membrane environment; the membrane cools naturally after power is turned off.

[0033] (2) Performance testing Response time: 3V, current density 30mA·cm -2 After that, the membrane surface temperature rose from 25°C to 36°C in 120 seconds, and the flux increased from 50 L·m⁻¹. -2 ・h -1 ・bar -1 Increased to 160L·m -2 ・h -1 ・bar -1 (On / Off ratio 3.2); Solvent resistance: After immersion in chloroform for 12 hours, the device's power-on response time remained at 130 seconds, and the throughput retention rate was 92%. Cyclic stability: After 50 consecutive on / off cycles (30 min on and 30 min off each time), the flux recovery rate was 91%, and the rejection rate (water-in-hexane emulsion) was consistently >99.5%. Self-cleaning performance: After simulating contamination (flux decay to 80% of initial value), applying a 5V, 5s electrothermal pulse restores the flux to 95% of the initial value.

[0034] Comparative example: Traditional external heating temperature response device Using PVDF as the base membrane, PNIPAm was grafted onto it via chemical initiation or conventional irradiation. This membrane was then placed in a conventional separation device that required external water bath circulation to heat the feed solution. Under the same test conditions: Response time: It takes 10 minutes to rise from 25°C to 36°C (5 times that of the present invention); Temperature fluctuation of the liquid material: Water bath heating caused the overall temperature of the liquid material to rise by 5°C; Solvent resistance: The membrane swells and ruptures after being immersed in chloroform for 12 hours, rendering it unable to function properly; It is significantly inferior to the "Joule-LCST integrated self-trigger valve" device of the present invention.

[0035] In summary, the innovation of this invention lies in: 1. In-situ Joule heating precise triggering mechanism By utilizing an intramembrane-through-cell (CNT) conductive network as a miniature electric heater, the heater and the PNIPAm functional layer are co-integrated, resulting in a short heat transfer path and small heat capacity, requiring only a low voltage of ≤5V and an A / cm² voltage of ≤50mA. -2 Joule heating can be generated at current density, enabling the PNIPAm layer at the orifice to rapidly cross the LCST (30-38℃), compressing the response time to 60-180s, and achieving a single-cycle energy consumption density of ≤0.5-3J·cm⁻¹. -2 It can reduce the overall temperature disturbance of the liquid by ≤2℃, thus solving the problems of slow response, high energy consumption and poor adaptability of traditional external heating systems.

[0036] 2. Co-design of the orifice confinement functional layer and conductive network By precisely confining the PNIPAm functional layer to a depth of 0.2-2 μm on the membrane surface (pore area), while ensuring that the CNT conductive network is above the percolation threshold and is uniform in-plane, the PNIPAm functional layer is guaranteed to ensure the dramatic and reversible abrupt change in wettability (water contact angle ≤25° at 25℃, ≥95° at 40℃) and flux (on / off ratio ≥3) before and after LCST, while avoiding the response delay caused by excessively thick functional layers. This solves the defects of uneven distribution of functional layers and imbalance between conductivity and response performance in traditional membranes.

[0037] 3. Integrated closed-loop intelligent control and self-cleaning A multi-dimensional online detection system is constructed, consisting of "resistance-temperature proxy detection + NTC / RTD / FBG sensing + flux / differential pressure criteria". Paired with a PID / PWM pulse controller, the membrane surface temperature can be stably maintained at LCST±1℃. At the same time, a 3-10s electro-thermal pulse self-cleaning function is integrated, which can restore flux without disassembly when fouled. The flux recovery rate is ≥90% after ≥50 cycles, which breaks through the limitations of traditional devices that do not have closed-loop control and require offline cleaning.

[0038] 4. Solvent environment adaptability and safety design The composite membrane exhibits linear expansion of ≤3% and mass swelling of ≤8% after immersion in chloroform for 12 hours. The electrodes are dielectrically isolated to prevent electrolysis. The power supply unit complies with SELV standards (output ≤12V) and has a protection level ≥IP54. It balances solvent resistance stability with electrical safety, addressing the industry pain points of easy corrosion and high safety risks in solvent separation scenarios.

[0039] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a temperature-responsive polyetheretherketone (PEEK) separation membrane, characterized in that, include: Step 1: Prepare PEEK precursor; Step 2: Prepare PEEK modified powder; Step 3: Prepare a uniform dispersion of CNTs; Step 4: Prepare CNT / PEEK composite casting solution; Step 5: Prepare CNT / PEEK composite porous membrane using the NIPS method; Step 6: Graft temperature-responsive groups by ultraviolet irradiation.

2. The preparation method according to claim 1, characterized in that, The method for preparing the PEEK precursor in step 1 includes: Under a nitrogen atmosphere, PEEK powder was dissolved in a mixed solvent of anhydrous dichloromethane and trifluoroacetic acid. 1,3-propanedithiol and p-toluenesulfonic acid were added, and after stirring, methanol was poured in to precipitate the mixture. The precipitate was then dried to obtain the PEEK precursor. The molar ratio of 1,3-propanedithiol to PEEK powder is 2:1 to 3:1; The molar ratio of p-toluenesulfonic acid to PEEK powder is 0.05:1 to 1:

1.

3. The preparation method according to claim 1, characterized in that, The method for preparing PEEK modified powder in step 2 includes: dissolving the PEEK precursor in anhydrous dichloromethane, adding 1,2-ethylene glycol and NBS, stirring, pouring in methanol to precipitate the precipitate, washing and drying to obtain PEEK modified powder; wherein The molar ratio of 1,2-ethylene glycol to PEEK precursor is 3:1 to 4:1; The molar ratio of NBS to PEEK precursor is 1:1 to 2:

1.

4. The preparation method according to claim 1, characterized in that, The method for preparing a uniform CNT dispersion in step 3 includes: CNT powder, dispersant, and deionized water were mixed and then mechanically stirred and ultrasonically dispersed to obtain a uniform CNT dispersion. The solid-liquid ratio of CNT powder in deionized water is controlled at 0.2~1.0 g / L; The mass ratio of CNT to dispersant is 1:2 to 1:4; The dispersant is Triton X-100 or sodium dodecyl sulfate.

5. The preparation method according to claim 1, characterized in that, The method for preparing the CNT / PEEK composite casting solution in step 4 includes: mixing PEEK modified powder and CNT uniform dispersion at a mass ratio of 1:1, adding ionic liquids [BMIM] BF4, THF, and DMAc, and then mechanically stirring, ultrasonically dispersing, and centrifuging to remove impurities to obtain the composite casting solution; wherein The amount of the ionic liquid [BMIM] BF4 added is 3-12 wt%; The volume ratio of THF to DMAc is 2:1; The total solids content of the composite casting solution is 10-15% w / w; The residual amount of ionic liquid [BMIM] BF4 after extraction and washing is ≤100ppm.

6. The preparation method according to claim 1, characterized in that, Step 5, the preparation of the CNT / PEEK composite porous membrane using the NIPS method, includes: After the composite casting solution was coated and placed at room temperature, it was then immersed in a deionized water coagulation bath for curing, resulting in a CNT / PEEK composite porous membrane. The wet film thickness is 150-200μm, and the room temperature storage time is 0.1-0.5 hours; The coagulation bath temperature is 25℃, and the curing time is 4 hours; Soaking time is 24 hours.

7. The preparation method according to claim 1, characterized in that, The method of grafting temperature-responsive groups with ultraviolet irradiation in step 6 includes: The composite porous membrane was immersed in a 3M NIPAm ethanol solution, irradiated with ultraviolet light, and washed to obtain a composite separation membrane.

8. A temperature-responsive polyetheretherketone (PEEK) separation membrane, prepared by the preparation method according to any one of claims 1-7, characterized in that, It has at least one of the following characteristics: PNIPAm is confined to 0.2-2 μm; CNT content is 20-60 wt%; LCST is 30-38℃; After soaking in chloroform for 12 hours, the linear expansion is ≤3% and the mass swelling is ≤8%. The tensile strength is 30-40% higher than that of pure PEEK film; At 25℃, the water contact angle is ≤25°; at 40℃, the water contact angle is ≥95°. The retention rate is ≥99.5% when separating oil-in-water emulsions.

9. A Joule-LCST integrated self-triggering valve device, characterized in that, include: The composite separation membrane employs the temperature-responsive polyether ether ketone separation membrane as described in claim 8, which contains a CNT conductive network and an orifice-confining PNIPAm layer. Electrodes electrically connected to the CNT conductive network are disposed on both sides of the composite separation membrane; The power module is connected to the electrodes; An online detection unit is used to detect the temperature of the composite separation membrane; The controller is used to control the power module to apply or turn off the voltage to the CNT conductive network of the composite separation membrane as needed, so as to control the temperature of the composite separation membrane within a preset range.

10. A method for separating the electrically triggered temperature response of the Joule-LCST integrated self-triggering valve device as described in claim 9, characterized in that, Includes the following steps: 1) Separation is performed at room temperature using a hydrophilic / underwater superoleophobic separation mode; 2) When flux needs to be turned on, apply a voltage of ≤5V to the CNT conductive network, control the membrane surface temperature in a closed loop to 38-40℃, and switch to hydrophobic / oleophilic mode; 3) When the flow needs to be shut off, disconnect the power and cool down to ≤30℃ to restore the hydrophilic / underwater superoleophobic mode; 4) When the flux decays to below 80% of its initial value, apply a 5-12V voltage for 3-10s electrothermal pulse, followed by water backflushing to achieve self-cleaning and restore the flux.

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