A gas-responsive intelligent super-amphiphobic oil-water separation membrane material and a preparation method and application thereof

Abstract

The application discloses a kind of gas response intelligent super double water-oil repellent separation membrane materials and its preparation method and application, preparation method includes first by silica nanoparticle template method preparation hydrophilic π-conjugated polymer nanoparticles;Then by spraying or layer-by-layer self-assembly method, negative polyacrylic acid polyelectrolyte with positive hydrophilic π-conjugated polymer nanoparticles are deposited on the substrate of reticular structure or porous structure, obtain porous nanostructure coating;Finally, perfluoroalkanoic acid is modified, the obtained gas response intelligent super double water-oil repellent separation membrane material can realize intelligent conversion between super double water-oil repellent from oil adhesion under gas stimulation response, gas response is rapid, anti-oil pollution, self-cleaning ability is strong, realizes fast oil-water separation, solves the separation failure problem caused by the insufficient self-cleaning ability of existing special wetting oil-water separation membrane material, easy to be contaminated by viscous oil.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of intelligent materials, and particularly relates to a gas-responsive intelligent superamphiphobic oil-water separation membrane material and a preparation method and application thereof. BACKGROUND

[0002] Oil-water separation is required in the fields of oil enrichment, fuel dehydration and purification, oily wastewater treatment, and marine oil spill recovery. Membrane separation materials with special wettability are attracting much attention due to their advantages such as no energy consumption, low cost, high separation efficiency, high selectivity, simple operation, and environmental friendliness. Traditional superhydrophobic-superoleophilic oil-water separation membranes are prone to be adhered and clogged by high-viscosity oil substances due to the oleophilic property of the materials, which reduces the separation efficiency and increases the use and maintenance costs. Superhydrophilic-subaqueous superoleophobic oil-water separation membranes can avoid being contaminated by oil substances under water. However, the superhydrophilic-subaqueous superoleophobic separation membranes are difficult to self-clean and lose the separation function after being contaminated by oil substances in the dry state without water. Therefore, it is of great significance to develop an oil-water separation membrane material that can resist oil adhesion (contamination) and has high-efficiency self-cleaning function in both air and water.

[0003] Superamphiphobic membrane surfaces exhibit high anti-oil / water adhesion and self-cleaning ability in air environment, but it is difficult to apply superamphiphobic membrane materials to the field of oil-water separation. Intelligent oil-water separation materials can switch between different wettability under environmental stimuli (such as gas, electric potential, infrared light, temperature, pH value, etc.), and can be applied to controllable oil-water separation devices. However, such intelligent oil-water separation membrane materials are limited to the wettability conversion between superhydrophobic-superhydrophilic caused by external stimuli, and still cannot solve the problem of separation failure caused by oil contamination of the separation membrane.

[0004] In summary, the existing special wettability separation membrane materials have the following disadvantages when used for oil-water separation:

[0005] 1. The superhydrophobic-superoleophilic oil-water separation membrane is used for oil-water separation. Since the density of oil is usually lower than that of water, the layered oil is not conducive to contact the separation membrane under its own gravity. In addition, the oleophilic property of the superhydrophobic material is prone to be adhered and clogged by high-viscosity oil substances, which reduces the separation efficiency and increases the use and maintenance costs.

[0006] 2. Superhydrophilic-underwater superoleophobic oil-water separation membranes, due to their high surface energy, easily adsorb oily impurities from the air, altering their surface chemistry and causing oil-water separation failure, thus increasing maintenance and management costs. Although traditional superhydrophilic-underwater superoleophobic oil-water separation membrane materials are designed with a rough surface to enhance underwater oil adhesion resistance, these membranes become wetted by viscous oily substances once they come into contact with them in a dry, anhydrous state. Furthermore, they are difficult to self-clean underwater using their hydrophilicity, leading to separation failure.

[0007] 3. Intelligent oil-water separation materials can usually only achieve the conversion between superhydrophobic and superhydrophilic, and it is difficult to achieve the intelligent conversion between highly efficient oil-resistant superhydrophobic and superhydrophilic (underwater superoleophobic).

[0008] Therefore, there is an urgent need to develop a highly efficient, self-cleaning, intelligent oil-water separation membrane material that can switch between superhydrophobic and underwater superoleophobic properties under environmental stimuli. Summary of the Invention

[0009] To overcome the shortcomings of existing special wettability oil-water separation membrane materials, such as insufficient self-cleaning ability and susceptibility to separation failure due to viscous oil contamination, the main objective of this invention is to provide a gas-responsive intelligent superbihydrophobic membrane material. This material achieves an intelligent conversion between superbihydrophobic (anti-oil adhesion) and underwater superoleophobic (superhydrophilic) properties under gas stimulation response. It exhibits rapid gas response, resistance to oil contamination, strong self-cleaning ability, and the ability to achieve rapid oil-water separation.

[0010] Another objective of this invention is to provide a method for preparing the gas-responsive intelligent superbioleophobic water-separating membrane material. First, hydrophilic π-conjugated polymer nanoparticles are prepared using a silica nanoparticle template method. Then, negatively charged polyacrylic acid polyelectrolyte and positively charged hydrophilic π-conjugated polymer nanoparticles are deposited on a mesh or porous substrate using a spraying or layer-by-layer self-assembly method to obtain a porous nanostructure coating. Finally, a gas-responsive intelligent superbioleophobic water-separating membrane material with oil resistance and self-cleaning properties is prepared by further modifying it with perfluoroalkyl acid. The preparation method is simple.

[0011] Another object of the present invention is to provide the application of the gas-responsive smart superbihydrophobic membrane material in oil-water separation membranes.

[0012] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0013] This invention provides a method for preparing a gas-responsive smart superaerophobic-hydrophobic membrane material, comprising the following steps:

[0014] Step a: preparing core-shell structure hydrophilic π-conjugated polymer nanoparticles by silica nanoparticle template method, comprising: dissolving hydrophilic π-conjugated monomer oxidized polymerization initiator in solvent to obtain initiator solution; under stirring condition, silica nanoparticles are fully dispersed in the initiator solution, then hydrophilic π-conjugated monomer is quickly added, and reaction is carried out at room temperature and under continuous stirring for more than 6 hours; then, standing and depositing are carried out, supernatant is removed, and the obtained hydrophilic π-conjugated polymer nanoparticles are dispersed in water to obtain a hydrophilic π-conjugated polymer nanoparticle dispersion liquid of core-shell structure;

[0015] Step b: depositing porous nanostructure hydrophilic π-conjugated polymer silica nanoparticle coating on the surface of a substrate by layer-by-layer self-assembly method, comprising: the substrate is subjected to surface treatment by sequentially going through alkali washing to remove oil, acid solution immersion for corrosion activation, and deionized water cleaning; polyacrylic acid is added in water, and continuous stirring is carried out at room temperature until the polyacrylic acid is completely dissolved to obtain a polyacrylic acid solution; the surface-treated substrate is sequentially immersed in the polyacrylic acid solution and the hydrophilic π-conjugated polymer nanoparticle dispersion liquid under stirring condition, and 10-30 cycles are repeatedly carried out, and drying is carried out at a temperature of 50-60 ℃, so that the porous nanostructure hydrophilic π-conjugated polymer silica nanoparticle coating can be obtained on the surface of the substrate;

[0016] or the polyacrylic acid solution is added in the hydrophilic π-conjugated polymer nanoparticle dispersion liquid to obtain a spraying liquid, and the porous nanostructure hydrophilic π-conjugated polymer silica nanoparticle coating is formed on the surface of the substrate by spraying, brushing or soaking;

[0017] Step c: preparing a gas-responsive intelligent super-amphiphobic coating, comprising: dissolving a fluorination reagent in 95% ethanol to obtain a fluorination liquid, and the coating substrate obtained in step b is subjected to fluorination treatment by spraying, brushing or soaking.

[0018] Preferably, in step a, the particle size of the hydrophilic π-conjugated polymer nanoparticles is 50-100 nm.

[0019] Preferably, in step a, the particle size of the nanosilica is 20-30 nm.

[0020] Preferably, in step a, the hydrophilic π-conjugated monomer oxidized polymerization initiator is selected from one or more of ammonium persulfate, potassium persulfate, anhydrous ferric chloride and ferric chloride.

[0021] Preferably, in step a, the solvent is selected from one or more of acetonitrile, anhydrous ethanol (99.5%) or ethanol solution containing 5-50% water.

[0022] As preferred, in step a, the hydrophilic π-conjugated monomer is selected from one or more of pyrrole, 3,4-vinylene dioxythiophene, aniline.

[0023] As preferred, in step b, the substrate is selected from one or more of stainless steel mesh (>300 mesh), filter mesh (>300 mesh), sponge, filter paper, glass sheet.

[0024] As preferred, in step b, the acid or base is selected from one or more of 0.1 mol / L NaOH solution, concentrated ammonia, concentrated hydrochloric acid, 0.5 mol / L concentrated hydrochloric acid.

[0025] As preferred, in step b, the polyacrylic acid has a Mv molecular weight of 45,000-1,250,000.

[0026] As preferred, in step b, the polyacrylic acid solution is added to the hydrophilic π-conjugated polymer nanoparticle dispersion to obtain a spraying liquid, and a porous nanostructured hydrophilic π-conjugated polymer silica nanoparticle coating is formed on the surface of the substrate by spraying, brushing or soaking.

[0027] As preferred, in step c, the fluorinated reagent is selected from one or more of 1H, 1H, 2H, 2H-perfluoroheptanoic acid, 1H, 1H, 2H, 2H-perfluorooctanoic acid (PFOA), 1H, 1H, 2H, 2H-perfluorodecanoic acid.

[0028] The application also provides a gas-responsive intelligent super-amphiphobic oil-water separation membrane material, which is obtained by the preparation method of the gas-responsive intelligent super-amphiphobic oil-water separation membrane material, has a contact angle with water > 160° and a rolling angle < 5°, has a contact angle with mineral oil > 150° and a rolling angle < 10°, and under an ammonia gas atmosphere, the super-amphiphobic property is quickly converted into super-hydrophilic or underwater super-oleophobic property, the contact angle with water is 0°, and the contact angle with oil under water is > 150° and the rolling angle is < 10°.

[0029] The application also provides an application of the gas-responsive intelligent super-amphiphobic oil-water separation membrane material in an oil-water separation net or a gas sensor.

[0030] In some embodiments, polyacrylic acid polyelectrolyte and polypyrrole hydrophilic π-conjugated polymer nanoparticles are introduced on a net structure or porous structure material by spraying or layer-by-layer self-assembly method, and perfluoroalkanoic acid is further modified, and the specific preparation steps include:

[0031] (a) Preparation of core-shell structured polypyrrole / silica nanoparticles. 0.2 g of ferric chloride was dissolved in 200 mL of acetonitrile solvent to obtain a ferric chloride / acetonitrile solution; 0.1-0.2 g of silica nanoparticles (20-30 nm) was dispersed in the ferric chloride / acetonitrile solution under stirring; after sufficient dispersion, 1-2 mL of pyrrole monomer was quickly added, and the stirring was continued at room temperature for more than 6 hours to obtain dark blue core-shell structured polypyrrole / silica nanoparticles; after standing and sedimentation, the supernatant was removed, and the prepared polypyrrole / silica nanoparticles were dispersed in 200 mL of water, with a diameter of 50-100 nm.

[0032] (b) Application of layer-by-layer self-assembly method to deposit porous nanostructured polypyrrole / silica nanoparticles on the surface of stainless steel wire mesh. The stainless steel wire mesh was cleaned in 0.1 mol / L NaOH solution to remove oil, and then immersed in 0.5 mol / L hydrochloric acid solution for 20 min for corrosion activation, and then washed with deionized water for standby; 0.1 g of polyacrylic acid was added to 200 mL of water, and the stirring was continued at room temperature for more than 48 hours until the polyacrylic acid was completely dissolved; the cleaned and activated stainless steel wire mesh was sequentially immersed in the polyacrylic acid solution and the polypyrrole / silica nanoparticle dispersion under stirring, and the process was repeated for 10-30 cycles, and then dried at a temperature of 50-60°C to obtain a stainless steel wire mesh with polypyrrole / silica nanoparticles deposited on the surface, and the polypyrrole / silica nanoparticles deposited on the surface have a porous nanostructure.

[0033] (c) Preparation of ammonia-responsive superamphiphobic coating. 0.2 mol / L of 1H, 1H, 2H, 2H-perfluoroheptanoic acid was dissolved in 200 mL of 95% ethanol to prepare a fluorination solution. The stainless steel wire mesh with polypyrrole / silica nanoparticles was immersed in the fluorination solution for 10 min to obtain a superamphiphobic coating.

[0034] In some embodiments, the prepared intelligent superamphiphobic stainless steel wire mesh is used as an oil-water separation mesh. In the absence of ammonia gas, the waste engine oil-water mixture (1:3) cannot wet the superamphiphobic stainless steel wire mesh; in the presence of ammonia gas, water quickly permeates through the superamphiphobic stainless steel wire mesh, while the engine oil cannot permeate, achieving intelligent oil-water separation, and the oil-water separation efficiency is more than 95%. The coating dried at a temperature of 60°C can recover to a superamphiphobic state, and the superamphiphobic oil-water separation mesh can be recycled.

[0035] Compared with the prior art, the present application provides a gas-responsive intelligent superamphiphobic oil-water separation film material with oil-resistant adhesion and self-cleaning, which has the following beneficial effects:

[0036] (1) Constructing super-hydrophilic porous nano-structured coating. The hydrophilic π-conjugated polymer nanoparticles such as polypyrrole are prepared by using silica nanoparticles as templates, which are easy to control the particle size and simple to prepare. The negatively charged polyelectrolyte of polyacrylic acid and the positively charged polypyrrole nanoparticles are deposited on the stainless steel mesh or porous structure by layer-by-layer self-assembly to obtain the coating with a large number of hydrophilic cationic and anionic groups and a rougher porous nano-structure, which is conducive to realizing the super-hydrophilic and underwater super-oleophobic interface. During the heat treatment process, the high reactivity of polypyrrole nanoparticles makes the polypyrrole nanoparticles close to each other further react, which enhances the mechanical stability of the nano-structure of the coating.

[0037] (2) Preparing super-amphiphobic coating. The super-hydrophilic porous nano-structured coating is further modified by perfluoroalkanoic acid to reduce the surface energy of the coating, and the super-amphiphobic coating with water and oil adhesion resistance is obtained. The rough porous nano-structure is conducive to reducing the contact of oil on the solid surface of the coating, which enhances the anti-oil adhesion ability of the fluorinated coating, and solves the problem that the traditional special wetting oil-water separation net is easily contaminated by viscous oil, which leads to the decrease of oil-water separation efficiency and even failure.

[0038] (3) Using the response characteristics of polypyrrole nanoparticles to ammonia, the wettability of the super-amphiphobic coating is intelligently controlled to switch between super-amphiphobic and super-hydrophilic (underwater super-oleophobic). In the air environment, the adhesion of oil substances can be avoided; in the ammonia atmosphere, the coating changes to super-hydrophilic property, realizing underwater super-oleophobicity.

[0039] (3) Using the response characteristics of polypyrrole nanoparticles to ammonia, the wettability of the coating is switched between super-amphiphobic and super-hydrophilic (underwater super-oleophobic). In the air environment, the coating shows super-amphiphobic property, which can avoid the adhesion of oil substances; in the ammonia atmosphere, the coating changes to super-hydrophilic property, realizing underwater super-oleophobicity and anti-oil contamination adhesion property. At this time, a stable hydration layer is formed around the polypyrrole nanoparticles and polypyrrole polyelectrolyte, which prevents oil droplets from contacting the solid surface. Meanwhile, the rough porous nano-structure filled with water further reduces the contact of oil droplets on the solid surface, resulting in the anti-oil wetting and anti-oil adhesion of the coating. The oil-water separation net prepared by using this kind of ammonia-responsive intelligent super-amphiphobic coating can realize self-cleaning, anti-oil adhesion and anti-oil contamination blocking, which is conducive to the development of controllable oil-water separation technology with self-cleaning and anti-oil contamination adhesion.

[0040] (4) The super-amphiphobic coating preparation method is simple, the raw materials are widely available, the gas response speed is fast, and the anti-oil contamination adhesion ability is strong, which significantly reduces the use and maintenance cost. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1Schematic diagram of the intelligent oil-water separation device in the embodiment.

[0042] Figure 2 Polypyrrole / silica nanoparticle coating obtained by layer-by-layer self-assembly on the surface of a stainless steel wire mesh in the embodiment; the left drawing is a polypyrrole / silica nanoparticle coating wrapped on the surface of a stainless steel wire cylindrical fiber, showing a rough porous nanostructure; the right drawing is a SEM image of the coating at a local magnification, a large number of particles less than 100 nm are randomly combined together, forming a rich pore structure. DETAILED DESCRIPTION

[0043] The embodiments of the present application are described in detail below with reference to the accompanying drawings, the following embodiments are implemented on the premise of the technical solutions of the present application, detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0044] The materials and chemical reagents used in the following embodiments are one or several of the following:

[0045] Coating substrate: stainless steel mesh (> 300 mesh), filter mesh (> 300 mesh), sponge, filter paper, glass sheet.

[0046] Hydrophilic π-conjugated monomer: pyrrole, 3,4-vinylene dioxothiophene, aniline.

[0047] π-conjugated monomer oxidation polymerization initiator: ammonium persulfate, potassium persulfate, anhydrous ferric chloride, ferric chloride.

[0048] Solvent: acetonitrile, anhydrous ethanol (99.5%).

[0049] Acid / base: 0.1 mol / L NaOH, concentrated ammonia, concentrated hydrochloric acid, 0.5 mol / L concentrated hydrochloric acid.

[0050] Polyacrylic acid: polyacrylic acid (PAA, Mv ~ 1250000), polyacrylic acid (PAA, Mv ~ 450000).

[0051] Nanosilica: nanosilica (20-30 nm).

[0052] Fluorinated reagent: 1H, 1H, 2H, 2H-perfluoroheptanoic acid, 1H, 1H, 2H, 2H-perfluorooctanoic acid, 1H, 1H, 2H, 2H-perfluorodecanoic acid.

[0053] Embodiment 1

[0054] This embodiment prepares a gas-responsive smart superhydrophobic coating. First, hydrophilic polypyrrole π-conjugated polymer nanoparticles are prepared using a silica nanoparticle template method. Then, negatively charged polyacrylic acid polyelectrolyte and positively charged polypyrrole nanoparticles are deposited on a stainless steel wire mesh or porous structure by spraying or layer-by-layer self-assembly to obtain a porous nanostructure coating. Finally, by further modifying with perfluoroalkyl acid, a gas-responsive smart superhydrophobic oleophobic water separation membrane material with anti-oil pollution and self-cleaning properties is obtained. The specific preparation steps are as follows:

[0055] (a) Preparation of core-shell polypyrrole / silica nanoparticles using a silica template method. 0.2 g of ferric chloride was dissolved in 200 mL of acetonitrile, sealed, and stirred at room temperature to obtain a ferric chloride / acetonitrile solution. Under stirring, 0.1 g of silica nanoparticles (20–30 nm) were dispersed in the ferric chloride / acetonitrile solution. The silica nanoparticles were fully dispersed for 5 min under ultrasonic oscillation, followed by rapid addition of 1 mL of pyrrole monomer. Ultrasonic oscillation was continued for 10 min, and then the mixture was stirred with moderate magnetic force at room temperature for at least 6 hours to obtain deep blue core-shell polypyrrole / silica nanoparticles. After standing for at least 2 hours for sufficient deposition, the supernatant was removed, and the nanoparticles were dispersed in 200 mL of water for later use.

[0056] (b) A porous polypyrrole / silica nanoparticle structure was deposited on the surface of a stainless steel wire mesh using a layer-by-layer self-assembly method. The stainless steel wire mesh was cleaned and degreased in a 0.1 mol / L NaOH solution, then immersed in a 0.5 mol / L hydrochloric acid solution for 20 min for corrosion activation, and rinsed with deionized water. 0.1 g of polyacrylic acid (Mv: ~45000) was added to 200 mL of water and stirred continuously at room temperature for at least 48 hours until the polyacrylic acid was completely dissolved. The cleaned and activated stainless steel wire mesh was first immersed in the polyacrylic acid solution for at least 30 seconds, rinsed with deionized water, and then immersed in a polypyrrole / silica nanoparticle dispersion (under stirring) for at least 30 seconds. It was then removed and rinsed with deionized water. This process was repeated 10–30 times, followed by drying at 60°C to obtain a stainless steel wire mesh with polypyrrole / silica nanoparticles deposited on its surface.

[0057] Proof through SEM images ( Figure 2 The obtained polypyrrole / silica nanoparticle coating is well coated on the outer surface of circular stainless steel wire fibers, exhibiting a rough porous nanostructure with curved surfaces. The nanoparticle diameter is 50–100 nm. The nanoparticles are randomly linked together by polyacrylic acid polyelectrolyte, forming a random suspended porous structure, which is beneficial for achieving the superhydrophobic and amphoteric properties of the coating. The mechanical stability of the polypyrrole / silica nanoparticle coating is further enhanced after drying at 60°C, improving the practicality of the coating.

[0058] Spray coating of polypyrrole / silica nanoparticle coating: 0.1-0.5 mL of polyacrylic acid (Mv: ~45000) solution was slowly added into 200 mL of polypyrrole / silica nanoparticle dispersion under stirring to prepare a spray coating solution. The spray coating solution was uniformly sprayed on the surface of stainless steel mesh using a spray gun, and then dried at a temperature of 60 °C to obtain a porous nanostructured polypyrrole / silica nanoparticle coating.

[0059] (c) Preparation of smart superomniphobic coating with ammonia gas responsiveness. 0.2 mL of 1H, 1H, 2H, 2H-perfluoroheptanoic acid was dissolved in 200 mL of 95% ethanol to prepare a fluorination solution. The polypyrrole / silica nanoparticle stainless steel mesh was immersed (or sprayed) in the fluorination solution for 10 min, and after drying, a superomniphobic coating was obtained.

[0060] The wettability of the coating was characterized using a contact angle measuring instrument. The results showed that the superomniphobic coating had a contact angle >160° and a rolling angle <5° for water (4 μL) in an air environment; and a contact angle >150° and a rolling angle <10° for mineral oil (5 μL). Both water droplets (20 μL) and oil droplets (20 μL) could freely roll on the superomniphobic coating with the stainless steel mesh as the substrate, showing good self-cleaning properties of water and oil adhesion resistance. Under an ammonia gas atmosphere, the superomniphobic properties of the coating were quickly converted to superhydrophilic (superoleophobic under water) properties, and the wettability conversion time was <10 seconds. The coating still maintained an oil contact angle (mineral oil, 5 μL) >150° (coating not wetted by water) in a gas environment with ammonia gas, but the contact angle of water (4 μL) was 0°, showing superoleophobic-superhydrophilic properties. When placed under water, the coating had an oil (dichloromethane, 5 μL) contact angle >150° and a rolling angle <10°, and the coating had very low adhesion to oil droplets, showing underwater superoleophobic properties.

[0061] Application Example 1

[0062] The smart superomniphobic stainless steel mesh with ammonia gas responsive superomniphobic coating prepared in Example 1 was applied to a controllable oil-water separation mesh. As shown in FIG. 1, the mesh was placed in a beaker containing water, and the water was stirred to generate water vapor. The water vapor was adsorbed by the mesh, and the mesh was filled with water vapor. When the mesh was placed in a beaker containing oil, the oil was adsorbed by the mesh, and the mesh was filled with oil. The mesh could be used for oil-water separation. Figure 1As shown, the application of super-biphobic stainless steel wire mesh to construct a simple oil-water separation device, using gravity method to directly separate various types of oil-water mixture, including restaurant source edible oil-water mixture (about 1:1), mechanical plant, ship source of waste oil-water mixture (about 1:3). In the absence of ammonia gas atmosphere, waste oil-water mixture (1:3) is stirred into emulsion, quickly poured into a simple oil-water separation device, waste oil-water mixture of oil and water can not be immersed in super-biphobic stainless steel wire mesh, coating remains clean, no water, oil wetting coating state; In the lower end of the super-biphobic separation net into ammonia gas atmosphere, the coating is converted to super-oleophobic-super-hydrophilic (underwater super-oleophobic) properties, water quickly infiltrate and through the coating, while waste oil can not penetrate or adhere to the coating, coating is trapped above the coating, thus realizing the intelligent oil-water separation of ammonia gas response.

[0063] By recycling the water phase and the oil phase, the oil-water separation efficiency is calculated to be 95%, which shows that the prepared intelligent super-biphobic oil-water separation net has good practicability. The prepared super-biphobic oil-water separation net can realize self-cleaning and oil adhesion resistance in both super-biphobic state and converted super-hydrophilic state. The coating dried at 60℃ can recover to super-biphobic state, which can be recycled and reduce cost.

[0064] The above description of the embodiments is to facilitate the understanding and use of the present application by those skilled in the art. Those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without having to go through creative labor. Therefore, the present application is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art according to the principles of the present application without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A method for preparing an ammonia-responsive smart superbihydrophobic membrane material, characterized in that, Includes the following steps: Step a: Prepare core-shell structured hydrophilic π-conjugated polymer nanoparticles using a silica nanoparticle template method, comprising: dissolving a hydrophilic π-conjugated monomer oxidative polymerization initiator in a solvent to obtain an initiator solution; under stirring conditions, fully dispersing silica nanoparticles in the initiator solution, then rapidly adding the hydrophilic π-conjugated monomer, reacting for more than 6 hours at room temperature and with continuous stirring; then allowing to settle, removing the supernatant to obtain hydrophilic π-conjugated polymer nanoparticles, dispersing them in water to obtain a core-shell structured hydrophilic π-conjugated polymer nanoparticle dispersion; Step b: A porous nanostructured hydrophilic π-conjugated polymer silica nanoparticle coating is deposited on the substrate surface using a layer-by-layer self-assembly method, comprising: the substrate being subjected to surface treatment in sequence by alkaline washing to remove oil, acid solution immersion for corrosion activation, and deionized water cleaning; polyacrylic acid is added to water and stirred continuously at room temperature until the polyacrylic acid is completely dissolved to obtain a polyacrylic acid solution; under stirring conditions, the surface-treated substrate is sequentially immersed in the polyacrylic acid solution and the hydrophilic π-conjugated polymer nanoparticle dispersion, repeated for 10 to 30 cycles, and dried at a temperature of 50 to 60°C, thereby obtaining a porous nanostructured hydrophilic π-conjugated polymer silica nanoparticle coating on the substrate surface; Alternatively, a polyacrylic acid solution can be added to the hydrophilic π-conjugated polymer nanoparticle dispersion to obtain a spraying solution, which can be used to form a porous nanostructured hydrophilic π-conjugated polymer silica nanoparticle coating on the substrate surface by spraying, brushing or wetting. Step c: Prepare an ammonia-responsive smart superhydrophobic coating, including: dissolving a fluorinating agent in 95% ethanol to obtain a fluorinated solution; and subjecting the coating substrate obtained in step b to fluorination treatment by spraying, brushing, or dipping. In step a, the hydrophilic π-conjugated monomer is selected from one or more of pyrrole, 3,4-vinyldioxythiophene, and aniline; the hydrophilic π-conjugated polymer nanoparticles have a particle size of 50–100 nm; the silica nanoparticles have a particle size of 20–30 nm; the hydrophilic π-conjugated monomer oxidative polymerization initiator is selected from one or more of ammonium persulfate, potassium persulfate, and ferric chloride; and the solvent is selected from one or more of acetonitrile, anhydrous ethanol with a purity of 99.5%, or an ethanol solution containing 5–50% water. In step b, the substrate is selected from one or more of the following: filter screen with a mesh size greater than 300, sponge, filter paper, and glass plate; The alkali is a 0.1 mol / L NaOH solution; The acid is 0.5 mol / L hydrochloric acid; The Mv molecular weight of the polyacrylic acid is 45,000 to 1,250,000. In step c, the fluorinating agent is selected from one or more of 1H,1H,2H,2H-perfluoroheptanoic acid, 1H,1H,2H,2H-perfluorooctanoic acid, and 1H,1H,2H,2H-perfluorodecanoic acid.

2. An ammonia-responsive smart superbihydrophobic membrane material, characterized in that, The ammonia-responsive smart superbihydrophobic water separation membrane material, prepared by the method described in claim 1, exhibits a contact angle >160° and a roll-off angle <5° for water; a contact angle >150° and a roll-off angle <10° for mineral oil; and under an ammonia atmosphere, its superbihydrophobic properties rapidly transform into superhydrophilic or underwater superoleophobic properties, with a water contact angle of 0° and an underwater oil contact angle >150° and a roll-off angle <10°.

3. The application of the ammonia-responsive smart superbihydrophobic membrane material according to claim 2 in oil-water separation networks or gas sensors.

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