Submerged super-amphiphobic porous material with high oil stain resistance and preparation method thereof

Abstract

The invention discloses a submerged super-amphiphobic porous material with high oil stain resistance and a preparation method thereof, and belongs to the technical field of material preparation. Aiming at the problems of pollution and insufficient long-term stability caused by oil drop adsorption of the existing submerged super-amphiphobic material in oil-water separation, a polyvinyl alcohol-tannic acid (PVA-TA) hydrophilic layer is constructed on the surface of a porous substrate, and an amino-terminated polydimethylsiloxane (PDMS) molecular brush is grafted by Schiff base reaction. The Si-O bond angle of the PDMS main chain is about 143 degrees, so that the molecular chain is excellent in flexibility, dynamically swings in a liquid environment to form a mechanical cleaning effect, and is combined with a low surface energy characteristic to synergistically inhibit droplet adsorption; meanwhile, the terminal amino group of PDMS and the PVA-TA network are stably combined through chemical bonding, and the under-liquid super-amphiphobic core performance of the material is reserved. The anti-pollution capability and long-term operation stability of the material are remarkably improved, the material is suitable for industrial oily wastewater treatment, offshore spilled oil recovery and other scenes, the preparation process is simple, large-scale production is easy, and the material has important industrialization value.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation technology and relates to a method for preparing a liquid-borne superhydrophobic porous material with high oil resistance. Specifically, it relates to a method that obtains a material by constructing a hydrophilic layer on the surface of a porous substrate and chemically grafting a flexible polydimethylsiloxane molecular brush, which has both liquid-borne superhydrophobic and dynamic antifouling properties. Background Technology

[0002] With the growth of global oil consumption, the problem of oily wastewater discharge is becoming increasingly serious. When such wastewater enters natural water bodies, it not only causes oil deposition, water quality deterioration, and disruption of aquatic ecological balance, but may also accumulate through the food chain and ultimately endanger human health. Therefore, the development of efficient, economical, environmentally friendly, and easy-to-operate oil-water separation technologies and materials has become a research hotspot for addressing oil spills and industrial wastewater pollution.

[0003] In recent years, researchers have successively developed a variety of intelligent wettability switching materials that can respond to external stimuli such as pH and temperature for oil-water separation. However, these materials usually depend on specific stimulus conditions, have complex operation steps, and limited separation efficiency, making them difficult to meet the needs of large-scale applications. In contrast, submerged superhydrophobic (superoleophobic in water and superhydrophobic in oil) porous materials do not depend on external stimuli. They can achieve reversible control of surface wettability through continuous phase pre-wetting treatment, exhibiting excellent separation capabilities for both oil-in-water emulsions and water-in-oil emulsions. This demonstrates outstanding application potential and is of great significance for promoting the practical development of oil-water separation technology.

[0004] However, existing superhydrophobic materials under liquid conditions face serious contamination problems in practical applications: on the one hand, tiny oil droplets in water-in-oil emulsions are easily adsorbed and aggregated on the material surface, forming a stubborn oily layer that damages the superhydrophobic micro-nano structure and causes a rapid decrease in separation flux; on the other hand, surfactants and organic impurities contained in the emulsion are prone to interact with the material surface, further aggravating contamination and significantly shortening the material's service life. Summary of the Invention

[0005] This invention addresses the problem of oil droplets being easily adsorbed and deposited on the material surface and pores during emulsion separation using existing underwater superhydrophobic materials, due to van der Waals forces and interfacial tension, leading to contamination and clogging. Furthermore, it addresses the shortcomings of existing antifouling modification techniques, such as unstable grafted structures, easy damage to the core properties of underwater superhydrophobic materials, and short-lived antifouling effects. This invention provides a method for antifouling modification of underwater superhydrophobic porous materials by constructing stable, flexible polydimethylsiloxane molecular brushes. This method significantly improves the material's anti-oil contamination ability while fully preserving its core underwater superhydrophobic properties, thereby ensuring the long-term stability of the material during emulsion separation.

[0006] This invention utilizes amino-terminated polydimethylsiloxane (PDMS), whose Si-O bonds in the main chain have a characteristic bond angle of approximately 143°. This bond angle endows the molecular chain with excellent rotational freedom and conformational flexibility, enabling the PDMS molecular brush to exhibit significant dynamic oscillation capability in an aqueous environment. Based on this structural characteristic, the molecular brush can form a "mechanical sweeping effect" during emulsion separation through the continuous oscillation of chain segments, promptly disrupting the adsorption equilibrium of oil droplets on the material surface and pushing them away, thereby kinetically inhibiting oil droplet deposition and adhesion. On the other hand, the 143° bond angle promotes a loose arrangement of PDMS molecular chains, further reducing the surface energy of the material and weakening the thermodynamic affinity between oil droplets and the interface. Simultaneously, the amino groups at the PDMS terminals can form stable chemical bonds with the polyvinyl alcohol-tannic acid (PVA-TA) network. While maintaining the material's superhydrophobic properties in liquid, the synergistic effect of the bond angle-dominated flexible structure and low surface energy significantly improves the anti-oiling effect and long-term operational stability.

[0007] This invention provides a method for preparing a liquid-borne superhydrophobic porous material with high oil resistance, comprising the following steps: S1: Preparation of polyvinyl alcohol-tannic acid mixed solution: Add 10-50 parts by weight of polyvinyl alcohol and 10-50 parts by weight of tannic acid to a mixed solvent composed of ethanol and water, and stir to disperse to obtain a uniform mixed solution; wherein, the total amount of the mixed solvent is 2000-20000 parts by weight, and the volume ratio of ethanol to water is 1:0.5-2. S2: Using a 1 mol / L NaOH solution, adjust the pH of the mixed solution obtained in step S1 to 8.5~9.5; then add 1~10 parts by weight of amino-terminated polydimethylsiloxane, and react for 2~6 hours under stirring conditions of 55~65 ℃ and 300~800 r / min to obtain the modified treatment solution. S3: Substrate material immersion treatment: Immerse the porous substrate material in the modified treatment solution described in step S2, and ultrasonically soak for 2 h under the conditions of ultrasonic power of 600W and frequency of 40 kHz. S4: Post-treatment and drying: Take out the porous substrate material after step S3, immerse it in anhydrous ethanol, and wash it for 10 minutes under the same ultrasonic conditions; repeat the washing 3 times, and then place the material in an oven at 50~80℃ to dry to constant weight, thus obtaining a liquid-based superhydrophobic porous material with high oil resistance.

[0008] The technical solution of this invention is implemented as follows: A liquid-based superhydrophobic porous material with high oil resistance is characterized in that the material is prepared by immersing a porous substrate material in a modification treatment solution for reaction; the modification treatment solution contains an amino-terminated polydimethylsiloxane and a polyvinyl alcohol-tannic acid mixed solution, which forms a stable surface modification layer under alkaline conditions through a Schiff base reaction.

[0009] Furthermore, the mass ratio of polyvinyl alcohol to tannic acid in the polyvinyl alcohol-tannic acid mixed solution is 1:0.5~2.

[0010] Furthermore, the porous substrate material is one of polyvinylidene fluoride membrane, polytetrafluoroethylene membrane, polypropylene membrane, nylon membrane, cellulose filter membrane, nonwoven fabric, melamine foam, and polyurethane foam, with an average pore size of 0.1~10 μm and a porosity of 40%~98%.

[0011] To address the issues of existing superhydrophobic materials in liquid-based oil-in-water emulsion separation, such as clogging due to oil droplet adsorption and insufficient long-term operational stability, this invention uses a porous material as a substrate. A stable superhydrophilic layer is constructed using polyvinyl alcohol (PVA) and tannic acid, followed by grafting PDMS molecular brushes based on a Schiff base reaction. This method leverages the strong hydrophilicity of the PVA-tannic acid network and the hydrophobicity and dynamic properties of the flexible PDMS segments to form a synergistic antifouling mechanism: the PDMS segments dynamically oscillate and sweep away oil droplets during separation, inhibiting oil droplet adsorption and deposition at the source. While maintaining the core superhydrophobic properties of the material, it significantly improves its anti-oil fouling ability and structural stability. Furthermore, the preparation process uses an ethanol-water system as a solvent, with mild reaction conditions and simple steps, facilitating large-scale production. The resulting material is suitable for scenarios requiring long-term stable operation, such as industrial oily wastewater treatment and marine oil spill recovery. It possesses comprehensive advantages in simplifying processes, enhancing practical performance, and expanding application scope, demonstrating significant industrialization and promotion value. Attached Figure Description

[0012] Figure 1 This is a diagram showing the wettability of the product obtained in Example 1 in different media, wherein... Figure 1 (a) The surface wettability of the product obtained in Example 1 in air for water and oil. Figure 1 (b) is a static oil contact angle diagram of the product obtained in Example 1 underwater. Figure 1 (c) is a static water contact angle diagram of the product obtained in Example 1 under oil.

[0013] Figure 2 The images show scanning electron microscope (SEM) images of the liquid-borne superhydrophobic porous material with high oil resistance prepared in Example 1 and the porous material prepared in Comparative Example 1. Figure 2 (a) Figure 2 (a1) are low-magnification and high-magnification scanning electron microscope images of the porous material prepared in Example 1. Figure 2 (b) Figure 2 (b1) are low- and high-magnification scanning electron microscope images of the porous material prepared in Comparative Example 1.

[0014] Figure 3 The diagram shows the process of continuously separating and stably separating toluene-in-water emulsions using the porous materials prepared in Example 1 and Comparative Example 1 under vacuum pump assistance, along with digital photographs of the emulsions and filtrates, and images obtained using an inverted fluorescence digital microscope without an eyepiece; among them, Figure 3 (a) is a process diagram of oil-in-water emulsion separation of the liquid-borne superhydrophobic porous material with high oil resistance prepared in Example 1. Figure 3 (b) is a process diagram of oil-in-water emulsion separation of the porous material prepared in Comparative Example 1. Figure 3 (c) and Figure 3 (d) are digital photographs of the porous material emulsions and filtrates prepared in Example 1 and Comparative Example 1, respectively, and their corresponding images under an inverted fluorescence digital microscope without an eyepiece.

[0015] Figure 4 The separation efficiency of the liquid-based superhydrophobic porous material with high oil resistance prepared in Example 1 and the porous material prepared in Comparative Example 1 for continuous separation of water-in-toluene emulsion was measured. Each time, 100 mL of water-in-toluene emulsion was separated, and all the filtrate was taken out to measure its separation efficiency before separating the next 100 mL of water-in-toluene emulsion.

[0016] Figure 5 The figure shows the cyclic separation performance test of the liquid-borne superhydrophobic porous material with high oil resistance prepared in Example 1. The figure also shows the separation efficiency of the sample. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the embodiments shown in the accompanying drawings, but this does not constitute any limitation on the present invention.

[0018] Example 1: A liquid-based superhydrophobic porous material with high oil resistance was prepared by the following steps: (1) Preparation of polyvinyl alcohol-tannic acid mixed solution: 50 parts by weight of polyvinyl alcohol and 50 parts by weight of tannic acid were added to a mixed solvent composed of ethanol and water, and stirred to disperse to obtain a uniform mixed solution; wherein, the total amount of the mixed solvent was 10,000 parts by weight, and the volume ratio of ethanol to water was 1:1; (2) Using a NaOH solution with a concentration of 1 mol / L, the pH value of the mixed solution obtained in step (1) was adjusted to 9.0; then 5 parts by weight of amino-terminated polydimethylsiloxane were added, and the mixture was reacted for 2 hours under stirring conditions of 65 ℃ and 400 r / min to obtain a modified treatment solution; (3) Substrate material impregnation treatment: Polystyrene-based porous foam was immersed in the modified treatment solution in step (2), and ultrasonically soaked for 2 hours under the conditions of ultrasonic power of 600W and frequency of 40 kHz. h; (4) Post-treatment and drying: Take out the polystyrene-based porous foam after step (3), immerse it in anhydrous ethanol, and wash it for 10 minutes under the same ultrasonic conditions; repeat the washing 3 times, and then place the material in an oven at 80°C to dry to constant weight, thus obtaining a liquid-based super-dual porous material with high oil resistance.

[0019] Example 2: A liquid-based superhydrophobic porous material with high oil resistance was prepared by the following steps: (1) Preparation of polyvinyl alcohol-tannic acid mixed solution: 25 parts by weight of polyvinyl alcohol and 25 parts by weight of tannic acid were added to a mixed solvent composed of ethanol and water, and stirred to disperse to obtain a uniform mixed solution; wherein, the total amount of the mixed solvent was 5000 parts by weight, and the volume ratio of ethanol to water was 1:1; (2) Using a NaOH solution with a concentration of 1 mol / L, the pH value of the mixed solution obtained in step (1) was adjusted to 9.0; then 2 parts by weight of amino-terminated polydimethylsiloxane were added, and the mixture was reacted for 2 hours under stirring conditions of 65 ℃ and 400 r / min to obtain a modified treatment solution; (3) Substrate material impregnation treatment: The polyvinylidene fluoride membrane was immersed in the modified treatment solution in step (2), and ultrasonically soaked for 2 hours under the conditions of ultrasonic power of 600W and frequency of 40 kHz. h; (4) Post-treatment and drying: Take out the polyvinylidene fluoride membrane after step (3), immerse it in anhydrous ethanol, and wash it for 10 minutes under the same ultrasonic conditions; repeat the washing 3 times, and then place the material in an oven at 80°C to dry to constant weight, thus obtaining a liquid-based super-dual porous material with high oil resistance.

[0020] Example 3: A liquid-based superhydrophobic porous material with high oil resistance was prepared by the following steps: (1) Preparation of polyvinyl alcohol-tannic acid mixed solution: 40 parts by weight of polyvinyl alcohol and 40 parts by weight of tannic acid were added to a mixed solvent composed of ethanol and water, and stirred to disperse to obtain a uniform mixed solution; wherein, the total amount of the mixed solvent was 8000 parts by weight, and the volume ratio of ethanol to water was 1:1; (2) Using a NaOH solution with a concentration of 1 mol / L, the pH value of the mixed solution obtained in step (1) was adjusted to 9.0; then 4 parts by weight of amino-terminated polydimethylsiloxane were added, and the mixture was reacted for 2 hours under stirring conditions of 65 ℃ and 400 r / min to obtain a modified treatment solution; (3) Substrate material impregnation treatment: Polyurethane foam was immersed in the modified treatment solution in step (2), and ultrasonically soaked for 2 hours under the conditions of ultrasonic power of 600W and frequency of 40 kHz. h; (4) Post-treatment and drying: Take out the polyurethane foam after step (3), immerse it in anhydrous ethanol, and wash it for 10 minutes under the same ultrasonic conditions; repeat the washing 3 times, and then place the material in an oven at 80°C to dry to constant weight, thus obtaining a liquid super-dual porous material with high oil resistance.

[0021] Example 4: A liquid-based superhydrophobic porous material with high oil resistance was prepared by the following steps: (1) Preparation of polyvinyl alcohol-tannic acid mixed solution: 30 parts by weight of polyvinyl alcohol and 30 parts by weight of tannic acid were added to a mixed solvent composed of ethanol and water, and stirred to disperse to obtain a uniform mixed solution; wherein, the total amount of the mixed solvent was 7000 parts by weight, and the volume ratio of ethanol to water was 1:1; (2) Using a NaOH solution with a concentration of 1 mol / L, the pH value of the mixed solution obtained in step (1) was adjusted to 9.0; then 4 parts by weight of amino-terminated polydimethylsiloxane were added, and the mixture was reacted for 2 hours under stirring conditions of 65 ℃ and 400 r / min to obtain a modified treatment solution; (3) Substrate material impregnation treatment: The cellulose filter membrane was immersed in the modified treatment solution in step (2), and ultrasonically soaked for 2 hours under the conditions of ultrasonic power of 600W and frequency of 40 kHz. h; (4) Post-treatment and drying: Take out the cellulose filter membrane after step (3), immerse it in anhydrous ethanol, and wash it for 10 minutes under the same ultrasonic conditions; repeat the washing 3 times, and then place the material in an oven at 80°C to dry to constant weight, thus obtaining a liquid super-dual porous material with high oil resistance.

[0022] Example 5: A liquid-based superhydrophobic porous material with high oil resistance was prepared by the following steps: (1) Preparation of polyvinyl alcohol-tannic acid mixed solution: 10 parts by weight of polyvinyl alcohol and 10 parts by weight of tannic acid were added to a mixed solvent composed of ethanol and water, and stirred to disperse to obtain a uniform mixed solution; wherein, the total amount of the mixed solvent was 2000 parts by weight, and the volume ratio of ethanol to water was 1:1; (2) Using a NaOH solution with a concentration of 1 mol / L, the pH value of the mixed solution obtained in step (1) was adjusted to 9.0; then 1 part by weight of amino-terminated polydimethylsiloxane was added, and the mixture was reacted for 2 hours under stirring conditions of 65 ℃ and 400 r / min to obtain a modified treatment solution; (3) Substrate material impregnation treatment: Melamine foam was immersed in the modified treatment solution in step (2), and ultrasonically soaked for 2 hours under the conditions of ultrasonic power of 600W and frequency of 40 kHz. h; (4) Post-treatment and drying: Take out the melamine foam treated in step (3), immerse it in anhydrous ethanol, and wash it for 10 minutes under the same ultrasonic conditions; repeat the washing 3 times, and then dry the material in an oven at 80°C until constant weight, thus obtaining a liquid-based super-dual porous material with high oil resistance.

[0023] Comparative Example 1: An underwater superoleophobic porous material was prepared by the following steps: (1) Preparation of a polyvinyl alcohol-tannic acid mixed solution: 50 parts by weight of polyvinyl alcohol and 50 parts by weight of tannic acid were added to a mixed solvent composed of ethanol and water, and stirred to disperse to obtain a uniform mixed solution; wherein, the total amount of the mixed solvent was 10,000 parts by weight, and the volume ratio of ethanol to water was 1:1; (2) Using a NaOH solution with a concentration of 1 mol / L, the pH value of the mixed solution obtained in step (1) was adjusted to 9.0 to obtain a modified treatment solution; (3) Substrate material impregnation treatment: Polystyrene-based porous foam was immersed in the modified treatment solution in step (2), and ultrasonically soaked for 2 hours under the conditions of ultrasonic power of 600W and frequency of 40 kHz. h; (4) Post-treatment and drying: Take out the polystyrene-based porous foam after step (3), immerse it in anhydrous ethanol, and wash it for 10 minutes under the same ultrasonic conditions; repeat the washing 3 times, and then place the material in an oven at 80°C to dry to constant weight, thus obtaining the underwater superoleophobic porous material.

[0024] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0025] The performance tests involved in the embodiments of this invention are performed using the following methods: 1. Static contact angle test (WCA / OCA / UOCA / UWCA) Figure 1This paper presents the air surface wettability characteristics, underwater static oil contact angle, and underwater static water contact angle of the product of Example 1. The contact angle tests were conducted using an OCA25 testing instrument from Dataphysics, Germany, on the highly oil-resistant underwater super-dipholytic porous material prepared in Example 1. The tests covered the air surface water contact angle (WCA), oil contact angle (OCA), underwater oil contact angle (UOCA), and underwater water contact angle (UWCA). Figure 1 (a) is a static water and oil contact angle diagram of the product obtained in Example 1 in air. Figure 1 (b) is a diagram of the underwater static oil contact angle of the product obtained in Example 1. Figure 1 (c) is a static water contact angle diagram of the product oil obtained in Example 1; as shown Figure 1 As shown in (a), chloroform was stained with an oil-soluble pigment (Oil Red O); water was stained with a water-soluble pigment (Methylene Blue) to demonstrate macroscopic wetting properties and test its contact angle, proving that the product obtained in Example 1 is amphiphilic in air; furthermore, from Figure 1 (b) It can be seen that the underwater oleophobic angle of the product obtained in Example 1 is 156.1°. Figure 1 (c) It can be seen that the hydrophobic angle of the product obtained in Example 1 is 151.8° under oil; in summary, it has the characteristics of superhydrophobic under liquid.

[0026] 2. Scanning electron microscope image (SEM) Figure 2 Scanning electron microscope (SEM) images of the liquid-borne superhydrophobic porous material with high oil resistance prepared in Example 1 and the porous material prepared in Comparative Example 1 are shown. The morphology of the porous materials prepared in Example 1 and Comparative Example 1 was analyzed using a JSM-7500F scanning electron microscope with an accelerating voltage of 20.0 kV. Before testing, the samples underwent surface gold sputtering treatment. Figure 2 (a) Figure 2 (a1) are low- and high-magnification scanning electron microscope images of the porous material prepared in Comparative Example 1. Figure 2 (b) Figure 2 (b1) are low and high magnification scanning electron microscope images of the porous material prepared in Comparative Example 1 at different magnifications; it can be observed that the porous materials prepared in Example 1 and Comparative Example 1 both have uniform and continuous hierarchical nanopore sizes, and the surface of the framework is obviously covered with a layer of polymer, but there is no pore blockage, indicating that the modification method will not have an adverse effect on the separation of oil and water emulsions.

[0027] 3. Test for separating oil-in-water emulsions Figure 3 These are digital photographs of the continuous separation of anionic surfactant SDS-stabilized water-in-toluene emulsions using porous materials prepared in Example 1 and Comparative Example 1; wherein, Figure 3 (a) A flowchart illustrating the process of separating an oil-in-water emulsion from the porous material prepared in Example 1. Figure 3 (b) is a process diagram of oil-in-water emulsion separation of the porous material prepared in Comparative Example 1. Figure 3 (c) and Figure 3 (d) Macroscopic comparison images of the porous materials prepared in Example 1 and Comparative Example 1 before and after separation, and their corresponding images under an inverted fluorescence digital microscope without an eyepiece; the porous materials prepared in Example 1 and Comparative Example 1 were subjected to water-in-oil emulsion separation. The specific test methods were as follows: (1) Preparation of high-stability oil-water emulsion: Under the condition of V water: V oil = 99:1, 0.01 g / L SDS surfactant was added and stirred at 1500 r / min for 5 h to obtain a stable water-in-oil emulsion; (2) Separation of high-stability oil-water emulsion: as Figure 3 As shown in (a) and 3(b), the syringe tip (without the needle) is connected to a superwetting material, and the filtrate outlet of the superwetting material is connected to a conical flask (filtrate collection device). The prepared subsurface superhydrophobic porous material with high oil resistance is used to collect the oil-in-water emulsion via a pressure pump. The entire process is as follows: Figure 3 As shown in (a) and 3(b); finally, the liquids of the porous material prepared in Example 1 before and after water-in-oil emulsion separation were observed using an eyepiece-less inverted fluorescence digital microscope. Figure 3 (c) It can be seen that before separation, the milky white water-in-oil emulsion contained many oil droplets. After separation, a transparent aqueous phase was obtained, and no oil droplets were observed in the filtrate after separation. Figure 3 (d) The filtrate after separation began to become turbid after 300 mL; the above results preliminarily confirm that the porous material prepared in Example 1 has better antifouling performance than that prepared in Comparative Example 1, and can separate a larger volume of emulsion.

[0028] 4. Comparative test on continuous separation of large amounts of water-in-toluene emulsion Figure 4The separation efficiency of the submersible superhydrophobic porous material with high oil resistance prepared in Example 1 and the porous material prepared in Comparative Example 1 in the continuous separation of 1400 mL of anionic surfactant SDS-stabilized water-in-toluene emulsion was compared. During the separation process, 100 mL of filtrate was collected as a sampling point. After sampling, the 100 mL sample was discarded, and a new collection bottle was used to collect the next batch of filtrate. This continuous cyclic separation operation of "collection-sampling-discarding-replacing" was repeated until 14 sets of samples were collected. The separation efficiency was then tested and analyzed based on this series of samples. It can be seen that the porous material prepared in Comparative Example 1 showed a significant decrease in separation performance during the 5th separation cycle, indicating that it can only continuously separate a maximum of about 400 mL of water-in-toluene emulsion. In contrast, the submersible superhydrophobic porous material with high oil resistance prepared in Example 1 only showed a significant decrease in separation performance during the 10th separation cycle, indicating that it can only continuously separate a maximum of 900 mL of water-in-toluene emulsion. The separation volume of approximately mL of water-infused toluene emulsion doubled, demonstrating the material's antifouling properties.

[0029] 5. Cyclic Separation Performance Test Figure 5 This study tested the cyclic separation performance of the liquid-borne superhydrophobic porous material with high oil resistance prepared in Example 1. The cumulative continuous separation emulsion volume for a single cycle was set at 900 mL. Each cycle consisted of 300 mL of filtrate collected as a sampling node, with the filtrate from each node collected as samples and named sequentially as 0~300 mL, 300~600 mL, and 600~900 mL. Once the cumulative separation emulsion volume reached 900 mL, the next cycle was initiated, and this process was repeated five times. This was used to evaluate the material's performance stability during continuous separation. It can be seen that the separation efficiency of the sample remained at approximately 99.3% throughout the five cycles, demonstrating the sample's reusability.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a liquid-submerged superomniphobic porous material with high oil-repellent properties, characterized in that, The method comprises the following steps: S1: preparing a polyvinyl alcohol-tannic acid mixed solution: 10-50 parts by weight of polyvinyl alcohol and 10-50 parts by weight of tannic acid are added into a mixed solvent composed of ethanol and water, and stirred and dispersed to obtain a uniform mixed solution; wherein the total amount of the mixed solvent is 2000-20000 parts by weight, and the volume ratio of ethanol to water is 1:0.5-2; S2: using a NaOH solution with a concentration of 1 mol / L to adjust the pH value of the mixed solution obtained in step S1 to 8.5-9.5; then 1-10 parts by weight of amino-terminated polydimethylsiloxane is added, and the reaction is carried out at 55-65 ℃ under stirring at 300-800 r / min for 2-6 hours to obtain a modified treatment solution; S3: substrate material immersion treatment: the porous substrate material is immersed in the modified treatment solution of step S2, and ultrasonic immersion is carried out under the condition that the ultrasonic power is 600 W and the frequency is 40 kHz for 2 hours; S4: post-treatment and drying: the porous substrate material treated in step S3 is taken out, immersed in anhydrous ethanol, and washed under the same ultrasonic condition for 10 minutes; after repeating the washing for 3 times, the material is placed in an oven at 50-80 ℃ for drying to constant weight, and a liquid-submerged super-amphiphobic porous material with high oil stain resistance is obtained.

2. The production method according to claim 1, characterized by, In step S1, the mass ratio of polyvinyl alcohol to tannic acid is 1:0.5-2.

3. The preparation method according to claim 1, characterized in that, In step S2, the molecular weight of the amino-terminated polydimethylsiloxane is 1000-5000, and the ratio of the amino-terminated polydimethylsiloxane to the total mass of polyvinyl alcohol-tannic acid is 1:5-15.

4. The method of claim 1, wherein, In step S3, the porous substrate material is one of polyvinylidene fluoride film, polytetrafluoroethylene film, polypropylene film, nylon film, cellulose filter membrane, non-woven fabric, melamine foam, polyurethane foam, and polystyrene-based porous foam, the average pore size is 0.1-10 μm, and the porosity is 40%-98%.

5. A liquid-submerged superomniphilic porous material with high oil-repellent properties, characterized in that, Prepared by the preparation method of any one of claims 1-4.

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