Hierarchical porous aerogel thin films and in situ confined liquid films, and methods for producing and using the same

Abstract

This application provides a hierarchical porous aerogel thin film and an in situ confined liquid membrane, as well as methods for producing and using the same. The hierarchical porous aerogel thin film has micron-sized pores distributed on its surface, micron-sized channels, submicron-sized channels, and nano-sized three-dimensional network mesopores distributed within the hierarchical porous aerogel thin film, and pores corresponding to the micron-sized channels, submicron-sized channels, and nano-sized three-dimensional network mesopores are simultaneously distributed across the cross section of the hierarchical porous aerogel thin film. The hierarchical porous aerogel thin film can form an aerogel-based confined liquid membrane in situ during membrane emulsification and emulsion separation. The aerogel-based confined liquid membrane has excellent drag reduction and combines membrane emulsification and emulsion separation functions. When used in membrane emulsification, it can produce emulsions with a uniform size distribution, and when used in emulsion separation, it can achieve an oil-water separation efficiency of over 99%.

Description

[Technical Field]

[0001] (Related Applications) This application claims priority to a Chinese patent application filed on October 19, 2023, application number 202311360008.4, entitled "Hierarchical porous aerogel thin film and in situ confined liquid film, and manufacturing method and use thereof."

[0002] (Technical field) The present application belongs to the field of membrane technology, and specifically relates to a hierarchical porous aerogel thin film and its preparation method and application, a hierarchical porous aerogel-based in situ confined liquid membrane, a thin film assembly, a membrane emulsification method, an emulsion separation method and an emulsification apparatus. [Background technology]

[0003] Membrane emulsification has attracted widespread attention as a novel technique for preparing monodisperse emulsions. Membrane emulsification technology boasts advantages such as low energy consumption, mild preparation conditions, homogeneity, ease of operation, and easy amplification. Its applications include extraction and separation, biomedicine, the petroleum industry, and cosmetics. With the rapid development of membrane emulsification technology, membrane emulsification materials include ceramic membranes such as alumina, zirconia, and silicon oxide; organic membranes such as polytetrafluoroethylene, polyethylene, polypropylene, and polycarbonate; and metal membranes such as nickel sieve plate membranes, stainless steel sieve plate membranes, and microchannel chips. One of the more commonly used membranes is the double-continuous narrow-pore-size-distribution glass membrane (SPG), formed by sintering special Japanese activated volcanic lime using a phase separation method. The SPG membrane has pores with the same three-dimensional network structure inside and outside, and the dispersed phase is easily removed during membrane emulsification. However, due to limitations in the adjustable pore size range, pore size distribution, porosity, surface properties, and pore shape, it cannot meet the needs of anti-fouling membrane emulsification technology or as an energy-saving membrane material.

[0004] Currently, existing porous membrane materials are prone to adsorption of small molecules due to their solid surface, causing membrane fouling and limiting their service life. In recent years, liquid materials have gradually attracted increasing attention due to their small intermolecular distances, strong interaction forces, and supermobility, allowing them to achieve multifunctional composites with solid matrices. Injecting liquids into self-supporting solid materials can provide a super-lubricating and anti-fouling interface on the surface, as well as precise gating and low-energy membrane channel transport in the composite.

[0005] Aerogel materials are novel porous materials with a three-dimensional nanomesh structure. They possess structural characteristics such as high porosity, high specific surface area, and ultralow density. Their unique structure has led to their significant applications in fields such as thermal insulation, gas adsorption and separation, water treatment, filtration and separation, and composite materials. Aramid aerogels, among others, possess excellent mechanical properties, chemical stability, and thermal stability (decomposition temperature up to 550°C). They can be used as self-supporting solid matrices with both flexibility and rigidity, providing ample confined space for functional liquids. However, existing solid-liquid composite membranes based on aramid aerogels require functional liquid infiltration before use, which is a relatively tedious process. Furthermore, functional liquid-infiltrated solid-liquid composite membranes typically require a large pressure differential across the membrane, requiring significant pressure for liquid passage. Furthermore, previously reported solid-liquid composite membranes have only performed a single function: membrane emulsification or membrane separation, limiting their use scenarios. Summary of the Invention [Problem to be solved by the invention]

[0006] In order to solve all or part of the above technical problems, this application provides the following technical solutions: [Means for solving the problem]

[0007] A first objective of the present application is to provide a hierarchical porous aerogel thin film, which has micron-sized pores distributed on its surface and micron-sized channels, submicron-sized channels, and nano-sized three-dimensional network mesopores distributed within it.Pores corresponding to the micron-sized channels, submicron-sized channels, and nano-sized three-dimensional network mesopores are simultaneously distributed across the cross section of the hierarchical porous aerogel thin film.

[0008] The hierarchical porous aerogel thin film with the above structure can provide abundant confinement spaces for liquids on the micron, submicron, and nanometer scales. The confinement spaces formed allow for in situ liquid film formation when a sample passes through the aerogel film, thereby generating stimuli-responsive properties to achieve diverse membrane properties. The hierarchical porous aerogel thin film with the above structure can be simultaneously applied to the fields of membrane emulsification and emulsion separation.

[0009] In some embodiments, the micron-sized pores have a pore size of 20 to 80 μm.

[0010] In some embodiments, the micron-sized channels have a diameter of 20-50 μm.

[0011] In some embodiments, the submicron-sized channels have a diameter of 2 to 20 μm.

[0012] In some embodiments, the nano-sized three-dimensional network mesopores have a pore size of less than 50 nm.

[0013] In some embodiments, the micron-sized channels and submicron-sized channels are longitudinal channels. The term "longitudinal channels" used herein refers to the angle α between the channel and the membrane surface, which is defined as 0<α<180°. For example, the micron-sized channels and submicron-sized channels are longitudinal channels perpendicular or nearly perpendicular to the membrane surface, and the micron-sized channels and submicron-sized channels are hierarchically arranged in the thickness direction of the membrane. This technical solution has the following beneficial effects: When an emulsion contacts the membrane surface, water in the emulsion preferentially infiltrates the pore channels in the membrane to form an in-situ confined liquid membrane. This hierarchical pore in-situ confined liquid membrane can switch its thin film function by adjusting the pressure to achieve membrane emulsification and membrane separation as needed.

[0014] In some embodiments, the hierarchical pores of the hierarchical porous aerogel thin film are nanosized, three-dimensional network mesopores obtained by transient phase separation between Kevlar® nanofibers and a pore-forming polymer, followed by sol-gel conversion, solvent exchange, and drying. Specifically, the hierarchical porous aerogel thin film is obtained by the sol-gel process in which the Kevlar® nanofibers and the pore-forming polymer intertwined to form a polymer-rich phase and a polymer-poor phase, transient phase separation between the polymer-rich phase and the non-solvent phase to form finger-like micron-sized channels, delayed phase separation of the polymer-poor phase to form nanosized, three-dimensional network mesopores, followed by solvent exchange and drying. The drying process may be, for example, a specialized drying process such as vacuum drying (e.g., freeze drying), convection drying (e.g., supercritical drying), microwave drying, solar drying, dehumidification drying, furnace gas drying, or chemical drying.

[0015] Preferably, the high molecular weight polymer includes at least one of polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone, and more preferably includes polyvinylpyrrolidone.

[0016] In some embodiments, the pore area ratios of the three types of pores corresponding to the micron-sized channels, submicron-sized channels, and nano-sized three-dimensional network mesopores are 2-5%, 40-65%, and 30-68%, respectively.

[0017] In some embodiments, the hierarchical porous aerogel film has superhydrophilicity and superoleophilicity in air.

[0018] In some embodiments, the penetration rate of the aqueous phase into the hierarchical porous aerogel thin film is faster than the penetration rate of the oil phase into the hierarchical porous aerogel thin film, which has the beneficial effect of forming a confined liquid film in situ.

[0019] A second object of the present application is to provide a method for preparing a hierarchical porous aerogel thin film, which includes the steps of applying a cast film solution containing Kevlar® nanofibers and a polymer onto a substrate, followed by transferring the solution to a solidification bath to form a hierarchical porous hydrogel thin film, and then subjecting the hierarchical porous hydrogel thin film to a solvent exchange and drying treatment to obtain a hierarchical porous aerogel thin film.

[0020] The above preparation method involves applying a cast film solution containing Kevlar® nanofibers and a high molecular weight polymer onto a substrate, then transferring it to a solidification bath where transient phase separation occurs to obtain an aerogel thin film. This method allows for the production of a hierarchical porous aerogel thin film with micron-sized pores on the surface and micron-sized channels, submicron-sized channels, and nano-sized three-dimensional network mesopores in the cross section of the film.

[0021] In some embodiments, the method of applying the cast film solution onto a substrate comprises a single layer substrate method.

[0022] Furthermore, the single-layer substrate method includes the steps of coating the cast film solution on at least one surface of a substrate, then transferring it to a solidification bath to form a hierarchical porous hydrogel thin film, and subjecting the hierarchical porous hydrogel thin film to a solvent exchange and drying process to obtain a hierarchical porous aerogel thin film with vertical channels.

[0023] In some embodiments, the mass ratio of Kevlar® nanofiber and polymer in the cast film solution is 4:1 to 1:2, and if the mass ratio is too high or too low, the degree of phase separation will be weak.

[0024] In some embodiments, the Kevlar nanofibers have a fiber size of 200D to 1000D.

[0025] In some embodiments, the polymer comprises at least one of polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone. Preferably, the polymer comprises polyvinylpyrrolidone. More preferably, the average molecular weight of the polyvinylpyrrolidone is 8 kDa to 1,300 kDa, such as polyvinylpyrrolidone with an average molecular weight of 8,000 (K16), 24,000 (K23), 58,000 (K29), or 1,300,000 (K88). If the molecular weight is too low, transient phase separation is difficult to occur, while if the molecular weight is too high, the viscosity of the cast film solution increases.

[0026] In some embodiments, the method for preparing the cast film solution includes providing a Kevlar® nanofiber dispersion and adding the polymer to the Kevlar® nanofiber dispersion to obtain the cast film solution.

[0027] Furthermore, the method for preparing the Kevlar® nanofiber dispersion includes uniformly dispersing Kevlar® fibers, an alkaline modifier, and a viscosity reducer in dimethyl sulfoxide to obtain the Kevlar® nanofiber dispersion.

[0028] Furthermore, the alkaline modifier includes potassium tert-butoxide and / or potassium hydroxide, and the alkaline modifier provides at least a strong alkaline environment to decompose the Kevlar® fibers.

[0029] Additionally, the viscosity reducing agent includes methanol and / or ethanol to reduce the viscosity of the dispersion.

[0030] Furthermore, the concentration of Kevlar® nanofiber in the Kevlar® nanofiber dispersion is 1 to 3 wt %. If the concentration is too low, the strength of the prepared hierarchical porous aerogel thin film will be too low, and if the concentration is too high, the viscosity of the dispersion will be too high, resulting in uneven mixing.

[0031] Furthermore, the mass ratio of Kevlar (registered trademark) fiber, alkaline modifier, and viscosity reducer in the Kevlar (registered trademark) nanofiber dispersion is 1:1:1 to 2:2:1, preferably 1:1:1.

[0032] In some embodiments, the method of applying the cast film solution onto a substrate includes, but is not limited to, a squeegee application method.

[0033] Furthermore, the speed of the squeegee coating method is 5 to 10 mm / s, the spin coating time is 5 to 15 seconds, and the distance between the squeegee and the substrate is 250 to 1000 μm.

[0034] In some embodiments, the substrate comprises glass and / or aluminum foil.

[0035] In some embodiments, the solidification bath comprises water or a combination of water and ethanol.

[0036] Furthermore, when the solidification bath contains water and ethanol, the volume ratio of water to ethanol should be between 5:1 and 1:1. If the ethanol content is too high, the resulting hierarchical porous aerogel thin film will be nonuniform. Adjusting the volume ratio of water to ethanol allows for the control of the growth direction of micron-sized channels and fine micron-sized channels. The volume ratio of water to ethanol is preferably between 2:1 and 1:1, resulting in hierarchical porous aerogel thin films with vertical or nearly vertical micron-sized channels and fine micron-sized channels.

[0037] In some embodiments, the temperature of the solidification bath is 0 to 20°C. For example, a low-temperature solidification bath of 0 to 3°C may be used, which is advantageous for obtaining a hierarchical porous gel thin film having a dense surface. For example, a room-temperature solidification bath of 10 to 20°C may be used.

[0038] In some embodiments, the solvent exchange process employs a mixed solution containing tert-butanol and water, preferably in a volume ratio of tert-butanol to water of 1:1 to 1:4.

[0039] In some embodiments, the drying process comprises freeze-drying and / or supercritical drying. Preferably, the drying process comprises freeze-drying. More preferably, the freeze-drying comprises continuous drying at a temperature of -40 to -100°C and an atmospheric pressure of 5 to 100 kPa for 4 to 6 hours.

[0040] In some embodiments, the preparation method can adjust the number, pore size, and distribution of micron-sized pores in the hierarchical porous aerogel thin film, and the morphology, number, and distribution of micron-sized channels and submicron-sized channels, by adjusting at least one of the mass ratio of Kevlar® nanofibers and polymer in the cast film solution, the content of solvent in the cast film solution, the temperature of the solidification bath, the composition of the solidification bath, and the molecular weight of the polymer.

[0041] A third object of the present application is to provide a hierarchical porous aerogel thin film obtained by the above preparation method.

[0042] A fourth object of the present application is to provide a hierarchical porous aerogel-based in situ confined liquid membrane, which includes a hierarchical porous aerogel thin film according to any one of the above technical solutions, and a liquid infiltrated and filled in the hierarchical porous aerogel thin film.

[0043] In some embodiments, the hierarchical porous aerogel-based in-situ confined liquid membrane is formed in situ by filling a membrane emulsification sample or emulsion separation sample into the hierarchical porous aerogel thin film during membrane emulsification or emulsion separation. Compared with a solid-liquid composite membrane pre-filled with a functional liquid, the in-situ formed hierarchical porous aerogel-based in-situ confined liquid membrane has drag reduction and energy-saving effects, a long service life, is reusable, and has good anti-fouling properties.

[0044] In some embodiments, the hierarchical porous aerogel-based in situ confined liquid membrane can switch between membrane emulsification and emulsion separation functions in response to differences in sample injection pressure and / or injection flow rate.

[0045] In some embodiments, when the sample injection pressure is 30 to 45 kPa and / or the injection flow rate is 1 ml / min to 3 ml / min, the hierarchical porous aerogel-based in situ confined liquid membrane has at least a membrane emulsification function, and when the sample injection pressure is -0.09 to -0.1 MPa and / or the injection flow rate is 0.1 ml / min to 0.3 ml / min, the hierarchical porous aerogel-based in situ confined liquid membrane has at least an emulsion separation function.

[0046] In some embodiments, the hierarchical porous aerogel-based in situ confined liquid film has superoleophobic properties underwater.

[0047] A fifth object of the present application is to provide an application of the hierarchical porous aerogel thin film or the hierarchical porous aerogel-based in situ confined liquid membrane described in any one of the above technical solutions in membrane emulsification and / or emulsion separation.

[0048] The sixth object of the present application is to provide a thin film assembly, which includes multiple layers of the hierarchical porous aerogel thin film according to any one of the above technical solutions.

[0049] In some embodiments, the thin film assembly includes a plurality of the layered porous aerogel thin films stacked together, the layered porous aerogel thin films having longitudinal channels.

[0050] Furthermore, in the thin film assembly, the micron-sized channels in one hierarchical porous aerogel thin film are adjacent to the submicron-sized channels in another adjacent hierarchical porous aerogel thin film. The thin film assembly having this structure is applied to water-in-oil multiple emulsions obtained by membrane emulsification.

[0051] Furthermore, the thin film assembly has a two-layer structure, and the micron-sized channels of the first layered porous aerogel thin film are adjacent to the submicron-sized channels of the second layered porous aerogel thin film.

[0052] A seventh object of the present application is to provide a membrane emulsification method, including a direct membrane emulsification method or a premix membrane emulsification method.

[0053] The direct membrane emulsification method includes passing a dispersed phase through any one of the hierarchical porous aerogel thin film or any one of the thin film assemblies described above under the action of a pressure of 30 to 45 kPa and / or an injection rate of 1 ml / min to 3 ml / min, and then passing the dispersed phase through a continuous phase to obtain an emulsion.

[0054] The premixing membrane emulsification method includes passing a uniform premixed emulsion containing an oil phase, an aqueous phase, and an emulsifier through the hierarchical porous aerogel thin film described in any one of the above technical solutions or the thin film assembly described in any one of the above technical solutions under conditions of a pressure of 30 to 45 kPa and / or an injection rate of 1 ml / min to 3 ml / min to obtain an emulsion.

[0055] The emulsion size obtained by the above membrane emulsification method is uniformly distributed and small in size, and oil-in-water emulsions and water-in-oil multiple emulsions can be obtained, and the emulsification effect is good.

[0056] In some embodiments, the dispersed phase in the direct membrane emulsification method and the oil phase in the premix membrane emulsification method are water-insoluble organic substances, preferably at least one of dodecane, hexadecane, cyclohexane, mineral oil, paraffin, and dimethylsilane, and more preferably at least one of dodecane, hexadecane, and cyclohexane.

[0057] And / or, in the direct membrane emulsification method, after passing the dispersed phase through the thin film assembly, it is placed in a mixed solution containing a continuous phase and a surfactant, and the surfactant includes at least one of oleyl polyether-10 carboxylic acid, Tween 80, Tween 85, Span 80, Span 85, and sodium dodecyl sulfate, preferably oleyl polyether-10 carboxylic acid, which has the beneficial effect of providing a prepared primary emulsion with good stability and relatively uniform mixing compared to other surfactants.

[0058] In some embodiments, the volume ratio of the oil phase to the water phase in the premixed emulsion is 1:3 to 3:1.

[0059] In the pre-mix membrane emulsification method, the emulsifier includes at least one of oleyl polyether-10 carboxylic acid, Tween 80, Tween 85, Span 80, Span 85, and sodium dodecyl sulfate, and preferably includes oleyl polyether-10 carboxylic acid.

[0060] In some embodiments, the content of the emulsifier is 1% to 5% of the total mass of the premixed emulsion.

[0061] In some embodiments, the emulsion obtained by the membrane emulsification method is an oil-in-water emulsion and / or a water-in-oil emulsion. For example, in the direct membrane emulsification method, the emulsion obtained by employing a thin film assembly with a two-layer membrane structure is a water-in-oil multiple emulsion.

[0062] In some embodiments, the size distribution of the emulsion obtained by the membrane emulsification method is 0 to 10 μm. For example, the size distribution of the emulsion obtained by the membrane emulsification method is 0 to 10 μm, but not 0.

[0063] In some embodiments, the creaming index of the emulsion obtained by the membrane emulsification method is 54.7% to 78.8%.

[0064] An eighth object of the present application is to provide a method for emulsion separation, which includes passing a sample to be separated through the hierarchical porous aerogel thin film described in any one of the above technical solutions or the thin film assembly described in any one of the above technical solutions under the action of a pressure of -0.09 to -0.1 MPa and / or an injection rate of 0.1 ml / min to 0.3 ml / min to achieve emulsion separation.

[0065] In some embodiments, the emulsion separation method has an oil-water separation efficiency of greater than 99%.

[0066] A ninth object of the present application is to provide an emulsification device, the emulsification device comprising a liquid inlet channel, a membrane unit, and a driving mechanism. The membrane unit includes the hierarchical porous aerogel thin film described in any one of the technical solutions above or the thin film assembly described in any one of the technical solutions above. One end of the liquid inlet channel communicates with the membrane unit, and the sample to be emulsified is injected into the liquid inlet channel under the action of the driving mechanism and flows into the membrane unit for emulsification.

[0067] In some embodiments, the membrane unit includes a thin film assembly having the above-described two-layer membrane structure. That is, the micron-sized channels of the first layered porous aerogel thin film of the thin film assembly having the two-layer membrane structure are disposed adjacent to the submicron-sized channels of the second layered porous aerogel thin film, and the second layered porous aerogel thin film is disposed adjacent to the liquid inlet channel, so that the sample to be emulsified flows into the thin film assembly in a direction that first passes through the micron-sized channels of the second layered porous aerogel thin film. An emulsification device using a thin film assembly having the above-described structure and mounting features can prepare water-in-oil multiple emulsions. [Effects of the Invention]

[0068] Compared with the prior art, the present application has at least the following beneficial effects: (1) The aerogel thin film provided by this application has hierarchical porous characteristics at micron, submicron, and nano sizes, providing abundant domain-restricted space for liquids. During membrane emulsification and emulsion separation, the in-situ formed liquid membrane has the effects of reducing drag and saving energy, and can be simultaneously applied to membrane emulsification and emulsion separation under different driving pressures. When applied to membrane emulsification, the prepared emulsions are uniform in size and have a high creaming coefficient, making them suitable for primary, secondary, or even higher-level emulsification. When applied to emulsion separation, the oil-water separation efficiency is greater than 99%.

[0069] (2) This application provides a simple method for preparing the above-mentioned hierarchical porous aerogel thin film. Specifically, a polymer is added to a nanofiber sol to form a multi-component cast film solution. This cast film solution is then coated on a substrate and transferred to a solidification bath, where it undergoes transient phase separation to form a porous hydrogel thin film. After drying, the hierarchical porous aerogel thin film can be obtained. This method is low cost, has a short production cycle, and is easy to industrialize. By adjusting the relevant reaction conditions, the morphology, number, and distribution of micron-sized pores and channels on the surface of the hierarchical porous aerogel thin film can be tuned.

[0070] (3) The above-mentioned hierarchical porous aerogel thin film, in situ confined liquid membrane thin film assembly, and emulsification device can combine the functions of membrane emulsification and membrane separation, and can prepare oil-in-water emulsions and water-in-oil multiple emulsions. [Brief explanation of the drawings]

[0071] In order to more clearly describe the technical solutions in the embodiments of the present application or the prior art, the following will briefly describe the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these accompanying drawings without any creative work.

[0072] [Figure 1a] FIG. 1 shows a schematic diagram of a longitudinal channel hierarchical porous aerogel thin film prepared by a single-layer substrate method in one embodiment of the present application, and an in situ confined liquid film formed in situ after the hierarchical porous aerogel thin film was immersed in an emulsion. [Figure 1b] FIG. 1 is a schematic diagram of membrane emulsification using the in situ confined liquid membrane employed in one embodiment of the present application. [Figure 1c] FIG. 1 is a schematic diagram of membrane separation using the in situ confined liquid membrane in one embodiment of the present application. [Figure 2a]FIG. 1 is a cross-sectional view of a cold cathode scanning electron microscope of a hierarchical porous aerogel thin film prepared in Example 1 of the present application. [Figure 2b] FIG. 1 is a cross-sectional view of a cold cathode scanning electron microscope of a hierarchical porous aerogel thin film prepared in Example 2 of the present application. [Figure 2c] FIG. 1 is a cross-sectional view of a cold cathode scanning electron microscope of a hierarchical porous aerogel thin film prepared in Example 3 of the present application. [Figure 2d] FIG. 1 is a cross-sectional view of a cold cathode scanning electron microscope of a hierarchical porous aerogel thin film prepared in Example 4 of the present application. [Figure 2e] FIG. 1 is a cross-sectional view of a cold cathode scanning electron microscope of a hierarchical porous aerogel thin film prepared in Example 5 of the present application. [Figure 3] 1 is a statistical diagram of the number of micron-sized pores on the surface of the hierarchical porous aerogel thin films prepared in Examples 1, 2, 3, and 5 of the present application. [Figure 4] FIG. 1 is a pore size distribution diagram of the surface micron-sized pores of the hierarchical porous aerogel thin films prepared in Examples 1 to 4 of the present application. [Figure 5] FIG. 1 is a schematic diagram of nitrogen adsorption / desorption curves of the hierarchical porous aerogel thin films prepared in Examples 1 to 4 of the present application. [Figure 6] FIG. 1 is a statistical diagram of the surface micron-sized pore diameter, micron-sized channel length, and submicron-sized channel length of the hierarchical porous aerogel thin films prepared in Examples 5 and 6 of the present application. [Figure 7] 1A and 1B are cold-cathode scanning electron microscope images of the surface and cross section of the hierarchical porous aerogel thin films prepared in Examples 5 and 6 of the present application. [Figure 8a] FIG. 1 is a cross-sectional view of a cold cathode scanning electron microscope of a hierarchical porous aerogel thin film prepared in Example 7 of the present application. [Figure 8b] FIG. 1 is a cross-sectional view of a cold cathode scanning electron microscope of a hierarchical porous aerogel thin film prepared in Example 8 of the present application. [Figure 8c] FIG. 1 is a cross-sectional view of a cold cathode scanning electron microscope of a hierarchical porous aerogel thin film prepared in Example 9 of the present application. [Figure 8d]FIG. 1 is a cross-sectional view of a cold cathode scanning electron microscope of a hierarchical porous aerogel thin film prepared in Example 10 of the present application. [Figure 8e] FIG. 1 is a cross-sectional view of a cold cathode scanning electron microscope of a hierarchical porous aerogel thin film prepared in Example 11 of the present application. [Figure 9] 1 is a structural schematic diagram of an emulsification device 1 including a hierarchical porous aerogel thin film in the present application. [Figure 10] FIG. 1 shows the pressure difference across the emulsion membrane of the in situ formed liquid membrane in Example 12 of the present application and the preformed solid-liquid composite membrane in Comparative Example 1. [Figure 11a] FIG. 10 is a comparative diagram of the optical properties of emulsions before and after emulsification in Example 13 of the present application. [Figure 11b] FIG. 10 is a comparative diagram of the optical properties of emulsions before and after emulsification in Example 14 of the present application. [Figure 11c] FIG. 10 is a comparative optical diagram of emulsion before and after emulsification in Example 15 of the present application. [Figure 11d] FIG. 1 is a comparative diagram of the optical properties of emulsions before and after emulsification in Example 16 of the present application. [Figure 11e] FIG. 10 is a comparison diagram of the optical properties of emulsions before and after emulsification in Example 17 of the present application. [Figure 12] FIG. 2 is a graph showing the particle size distribution of emulsions before and after emulsification in Examples 13 to 17 of the present application. [Figure 13] FIG. 1 is a statistical diagram of emulsion particle sizes before and after emulsification in Examples 13 to 17 of the present application. [Figure 14] FIG. 2 is a structural schematic diagram of an emulsification device 2 including a membrane element with a two-layer membrane in Example 21 of the present application. [Figure 15] 1 is an optical photograph of the water-in-oil formulation prepared in Example 18 of the present application. [Figure 16] 1 shows optical photographs before and after emulsion separation for Sudan Red staining in Example 19 of the present application. [Figure 17] 1 shows the ultraviolet-near infrared spectra before and after emulsion separation for Sudan Red staining in Example 19 of the present application. [Figure 18] 1 shows Fourier infrared spectra before and after emulsion separation in Example 19 of the present application. [Figure 19] FIG. 1 shows a contact angle test of the hierarchical porous aerogel thin film prepared in Example 7 of the present application with cyclohexane in water and air. [Figure 20] FIG. 1 is a statistical graph of particle size over time for the emulsion prepared in Example 19 of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0073] In the following, the technical solution of the present application will be described in detail in connection with specific embodiments, so that those skilled in the art can better understand and implement the technical solution of the present application. The specific functional details disclosed in this specification should not be understood as limiting, but should only be understood as the basis for the claims, and should be interpreted as a representative basis for those skilled in the art to actually adopt the present application differently in any appropriately detailed embodiment.

[0074] Example 1 This example provides a hierarchical porous aerogel thin film with longitudinal channels and a method for preparing the same. 0.2g Kevlar® fiber, 0.2g potassium tert-butoxide, 0.2g methanol, and 10g dimethyl sulfoxide were mixed and stirred to obtain a Kevlar® fiber dispersion. 0.05g polyvinylpyrrolidone (molecular weight 1300000, K88) was added to the Kevlar® fiber dispersion and stirred continuously for 3 hours to form a completely uniform cast film solution. The solution was then left to stand for 4 hours to remove air bubbles and prepare a cast film solution. The cast film solution was applied using a single-substrate method. As shown in Figure 1a, a 500 μm-thick cast film solution 2 was rubbed onto aluminum foil paper 1 using a squeegee. The aluminum foil paper 1 coated with film solution 2 was then immersed in room-temperature deionized water. When the solution completely changed color from orange to pale yellow and became nearly transparent, it was peeled off from the substrate, yielding a thin hydrogel film. The hydrogel thin film was prepared by exchanging the water every 2 hours, 5 to 6 times. A mixed solution of tert-butanol and deionized water in a volume ratio of 1:1 was selected, and the solvent exchange was carried out for 4 hours. The mixture was then freeze-dried continuously for 4 hours at 40 to 100°C and an atmospheric pressure of 5 to 100 kPa to obtain a hierarchical porous aerogel thin film (4-1-K88).

[0075] The structure of the hierarchical porous aerogel thin film is shown in Figure 1a. The surface of the film contains micron-sized pores, and the interior contains vertical micron-sized channels, submicron-sized channels, and nano-sized three-dimensional network mesopores. The cross-sectional morphology of the 4-1-K88 film is shown in Figure 2a. The statistics of the number of micron-sized pores on the surface are shown in Figure 3. The pore size distribution is shown in Figure 4 (corresponding to the curve shown in Figure 4-1). The nitrogen adsorption / desorption curve is shown in Figure 5.

[0076] Example 2 This example provides a hierarchical porous aerogel thin film with longitudinal channels and a method for preparing the same. 0.6g Kevlar® fiber, 0.6g potassium tert-butoxide, 0.6g methanol, and 30g dimethyl sulfoxide were mixed and stirred to obtain a Kevlar® fiber dispersion. 0.2g polyvinylpyrrolidone (molecular weight 1300000, K88) was added to the Kevlar® fiber dispersion and stirred continuously for 3 hours to form a completely uniform cast film solution. The solution was then left to stand for 4 hours to remove air bubbles and prepare a cast film solution. The cast film solution was applied using a single-substrate method. As shown in Figure 1a, a 500 μm-thick layer of cast film solution 2 was applied to aluminum foil paper 1 using a squeegee. The aluminum foil paper 1 containing film solution 2 was then immersed in room-temperature deionized water. When the solution completely changed color from orange to pale yellow and became nearly transparent, it was peeled off from the substrate to obtain a hydrogel thin film. The hydrogel thin film was prepared by exchanging the water every 2 hours, 5 to 6 times. A mixed solution of tert-butanol and deionized water in a volume ratio of 1:1 was selected, and the solvent exchange was carried out for 4 hours. The mixture was then freeze-dried continuously for 4 hours at 40 to 100°C and an atmospheric pressure of 5 to 100 kPa to obtain a hierarchical porous aerogel thin film (3-1-K88).

[0077] The cross-sectional morphology of the membrane of 3-1-K88 is shown in Figure 2b, the statistics of the number of surface micron-sized pores are shown in Figure 3, the pore size distribution is shown in Figure 4 (corresponding to the curve shown in 3-1), and the nitrogen adsorption / desorption curve schematic is shown in Figure 5.

[0078] Example 3 This example provides a hierarchical porous aerogel thin film with longitudinal channels and a method for preparing the same. 0.2g Kevlar® fiber, 0.2g potassium tert-butoxide, 0.2g methanol, and 10g dimethyl sulfoxide were mixed and stirred to obtain a Kevlar® fiber dispersion. 0.4g polyvinylpyrrolidone (molecular weight 1300000, K88) was added to the Kevlar® fiber dispersion and stirred continuously for 3 hours to form a completely uniform cast film solution. The solution was then left to stand for 4 hours to remove air bubbles and prepare a cast film solution. The cast film solution was applied using a single substrate method. As shown in Figure 1a, a 500 μm-thick layer of cast film solution 2 was applied to aluminum foil paper 1 using a squeegee. The aluminum foil paper 1 containing film solution 2 was immersed in room temperature deionized water. When the solution completely changed color from orange to pale yellow and became nearly transparent, it was peeled off from the substrate to obtain a thin hydrogel film. The hydrogel thin film was prepared by exchanging the water every 2 hours, 5 to 6 times. A mixed solution of tert-butanol and deionized water in a volume ratio of 1:1 was selected, and the solvent exchange was carried out for 4 hours. The mixture was then freeze-dried continuously for 4 hours at 40 to 100°C and an atmospheric pressure of 5 to 100 kPa to obtain a hierarchical porous aerogel thin film (2-1-K88).

[0079] The cross-sectional morphology of the membrane of 2-1-K88 is shown in Figure 2c, the statistics of the number of surface micron-sized pores are shown in Figure 3, the pore size distribution is shown in Figure 4 (corresponding to the curve shown in 2-1), and the nitrogen adsorption / desorption curve schematic is shown in Figure 5.

[0080] Example 4 This example provides a hierarchical porous aerogel thin film with longitudinal channels and a method for preparing the same. 0.2g Kevlar® fiber, 0.2g potassium tert-butoxide, 0.2g methanol, and 10g dimethyl sulfoxide were mixed and stirred to obtain a Kevlar® fiber dispersion. 0.2g polyvinylpyrrolidone (molecular weight 1300000, K88) was added to the Kevlar® fiber dispersion and stirred continuously for 3 hours to form a completely uniform cast film solution. The solution was then left to stand for 4 hours to remove air bubbles and prepare a cast film solution. The cast film solution was applied using a single-substrate method. As shown in Figure 1a, a 500 μm-thick layer of cast film solution 2 was applied to aluminum foil paper 1 using a squeegee. The aluminum foil paper 1 containing film solution 2 was then immersed in room-temperature deionized water. When the solution completely changed color from orange to pale yellow and became nearly transparent, it was peeled off from the substrate to obtain a hydrogel thin film. The hydrogel thin film was prepared by exchanging the water every 2 hours, 5 to 6 times. A mixed solution of tert-butanol and deionized water in a volume ratio of 1:1 was selected, and the solvent exchange was carried out for 4 hours. The mixture is then freeze-dried continuously for 4 hours at 40 to 100°C and an atmospheric pressure of 5 to 100 kPa to obtain a hierarchical porous aerogel thin film (1-1-K88).

[0081] The membrane cross-sectional morphology of 1-1-K88 is shown in Figure 2d, the pore size distribution is shown in Figure 4 (corresponding to the curve shown in 1-1), and the nitrogen adsorption / desorption curve schematic is shown in Figure 5.

[0082] Example 5 This example provides a hierarchical porous aerogel thin film with longitudinal channels and a method for preparing the same. 0.2g Kevlar® fiber, 0.2g potassium tert-butoxide, 0.2g methanol, and 10g dimethyl sulfoxide were mixed and stirred to obtain a Kevlar® fiber dispersion. 0.4g polyvinylpyrrolidone (molecular weight 1300000, K88) was added to the Kevlar® fiber dispersion and stirred continuously for 3 hours to form a completely uniform cast film solution. The solution was then left to stand for 4 hours to remove air bubbles and prepare a cast film solution. The cast film solution was applied using a single substrate method. As shown in Figure 1a, a 500 μm-thick layer of cast film solution 2 was applied to aluminum foil paper 1 using a squeegee. The aluminum foil paper 1 containing film solution 2 was immersed in room temperature deionized water. When the solution completely changed color from orange to pale yellow and became nearly transparent, it was peeled off from the substrate, yielding a thin hydrogel film. The hydrogel thin film was prepared by exchanging the water every 2 hours, 5 to 6 times. A mixed solution of tert-butanol and deionized water in a volume ratio of 1:1 was selected, and the solvent exchange was carried out for 4 hours. The mixture is then freeze-dried continuously for 4 hours at 40 to 100°C and an atmospheric pressure of 5 to 100 kPa to obtain a hierarchical porous aerogel thin film (1-2-K88).

[0083] The cross-sectional morphology of the 1-2-K88 membrane is shown in Figure 2e, the statistics of the number of micron-sized pores on the surface are shown in Figure 3, the statistics of the micron-sized pore diameter, micron-sized channel length, and submicron-sized channel length are shown in Figure 6, and the cold cathode scanning electron microscope images of the surface and cross section are shown in Figure 7 (corresponding to a room temperature water solidification bath).

[0084] Example 6 This example provides a hierarchical porous aerogel thin film with longitudinal channels and a method for preparing the same. 0.2g Kevlar® fiber, 0.2g potassium tert-butoxide, 0.2g methanol, and 10g dimethyl sulfoxide were mixed and stirred to obtain a Kevlar® fiber dispersion. 0.4g polyvinylpyrrolidone (molecular weight 1300000, K88) was added to the Kevlar® fiber dispersion and stirred continuously for 3 hours to form a completely uniform cast film solution. The solution was then left to stand for 4 hours to remove air bubbles and prepare a cast film solution. The cast film solution was applied using a single substrate method. As shown in Figure 1a, a 500 μm-thick layer of cast film solution 2 was applied to aluminum foil paper 1 using a squeegee. The aluminum foil paper 1 containing film solution 2 was immersed in low-temperature deionized water at 3°C. When the solution completely changed color from orange to pale yellow and became nearly transparent, it was peeled off from the substrate, yielding a thin hydrogel film. The hydrogel thin film was prepared by exchanging the water every 2 hours, 5 to 6 times. A mixed solution of tert-butanol and deionized water in a volume ratio of 1:1 was selected, and the solvent exchange was carried out for 4 hours. The membrane is then freeze-dried continuously for 4 hours at 40-100°C and 5-100 kPa pressure to obtain a hierarchical porous aerogel thin film.

[0085] The statistical results of the surface micron pore size, micron-sized channel length, and submicron-sized channel length of the hierarchical porous aerogel thin film with longitudinal channels prepared in this example are shown in Figure 6, and its cross-sectional morphology and surface morphology (corresponding to an ice-water solidification bath) are shown in Figure 7. As can be seen from Figures 6 and 7, a hierarchical porous aerogel thin film with a dense surface and narrow channels can be prepared using a low-temperature solidification bath.

[0086] Example 7 This example provides a hierarchical porous aerogel thin film with longitudinal channels and a method for preparing the same. 0.2g Kevlar® fiber, 0.2g potassium tert-butoxide, 0.2g methanol, and 10g dimethyl sulfoxide were mixed and stirred to obtain a Kevlar® fiber dispersion. 0.4g polyvinylpyrrolidone (molecular weight 1300000, K88) was added to the Kevlar® fiber dispersion and stirred continuously for 3 hours to form a completely uniform cast film solution. The solution was then left to stand for 4 hours to remove air bubbles and prepare a cast film solution. The cast film solution was applied using a single-substrate method. As shown in Figure 1a, a 500 μm-thick layer of cast film solution 2 was applied to aluminum foil paper 1 using a squeegee. The aluminum foil paper 1 containing film solution 2 was immersed in a room-temperature solidification bath at 10°C containing a 5:1 volume ratio of deionized water and ethanol. When the solution completely changed from orange to pale yellow and became nearly transparent, it was peeled off from the substrate, yielding a thin hydrogel film. The hydrogel thin film was prepared by exchanging the water every 2 hours, 5 to 6 times. A mixed solution of tert-butanol and deionized water in a volume ratio of 1:1 was selected, and the solvent exchange was carried out for 4 hours. The membrane is then freeze-dried continuously for 4 hours at 40-100°C and 5-100 kPa pressure to obtain a hierarchical porous aerogel thin film.

[0087] The cross-sectional morphology of the hierarchical porous aerogel thin films with longitudinal channels prepared in this example is shown in Figure 8a, which shows significant differences in the channel size and morphology.

[0088] Example 8 Unlike Example 7, the molecular weight of the polyvinylpyrrolidone used in this example is 8000. Otherwise, a hierarchical porous aerogel thin film with a very narrow pore flow distribution was obtained in the same manner as in Example 7.

[0089] Example 9 Unlike Example 7, the molecular weight of the polyvinylpyrrolidone used in this example is 24000. Otherwise, a hierarchical porous aerogel thin film with a narrow pore flow distribution was obtained in the same manner as in Example 7.

[0090] Example 10 Unlike Example 7, the molecular weight of the polyvinylpyrrolidone used in this example is 58,000. Otherwise, a hierarchical porous aerogel thin film with a wide pore flow distribution was obtained in the same manner as in Example 7.

[0091] Example 11 Unlike Example 7, the solidification bath used in this example was a 4:1 volume ratio of deionized water and ethanol. The rest of the procedure was the same as in Example 7 to obtain a hierarchical porous aerogel thin film.

[0092] The cross-sectional morphology of the hierarchical porous aerogel thin film with longitudinal channels prepared in this example is shown in Figure 8b, and the channel morphology exhibits the same inclination angle.

[0093] Example 12 Unlike Example 7, the solidification bath used in this example was a 3:1 volume ratio of deionized water and ethanol. The rest of the procedure was the same as in Example 7 to obtain a hierarchical porous aerogel thin film.

[0094] The cross-sectional morphology of the hierarchical porous aerogel thin film with vertical channels prepared in this example is shown in Figure 8c, where the channel size begins to increase.

[0095] Example 13 Unlike Example 7, the solidification bath used in this example was a 2:1 volume ratio of deionized water and ethanol, and the other procedures were the same as in Example 7 to obtain a hierarchical porous aerogel thin film.

[0096] The cross-sectional morphology of the hierarchical porous aerogel thin film with vertical channels prepared in this example is shown in Figure 8d, which shows a large difference in the channel sizes.

[0097] Example 14 Unlike Example 7, the solidification bath used in this example was a 1:1 volume ratio of deionized water and ethanol, and the other procedures were the same as in Example 7 to obtain a hierarchical porous aerogel thin film.

[0098] The cross-sectional morphology of the hierarchical porous aerogel thin film with vertical channels prepared in this example is shown in Figure 8e, where the channel morphology changes from inclined to vertical and the size is uniform.

[0099] Example 15 This example provides a membrane emulsification method, shown in Figure 1b. The emulsification apparatus 1 shown in Figure 9 was used, which had a channel 10 and an aerogel thin film 12, in which the aerogel thin film 12 was a circular plate with a diameter of 25 mm cut out from the hierarchical porous aerogel thin film prepared in Example 13 of the present application. A homogeneous premixed emulsion 11 (premixed emulsion 11 with a volume ratio of 2:1 between dodecane and deionized water and containing 3% AKY by mass) was injected into channel 10 at a fixed flow rate of 1 ml / min. The pressure difference across the emulsion membrane was measured using a pressure sensor (PX2300-10BDI) until the mixed emulsion passed through the aerogel thin film 12. The test results are shown in Figure 10 (corresponding to the in situ formed liquid membrane curve), and the pressure difference across the emulsion membrane for the in situ formed hierarchical porous aerogel-based confined liquid membrane is 38.7 kPa.

[0100] (Comparative Example 1) Unlike Example 15, Comparative Example 1 first cut the hierarchical porous aerogel thin film prepared in Example 13 into a 25 mm diameter disk. The disk was immersed in the functional liquid perfluoropolyether lubricant DuPont Krytox 101 to obtain a solid-liquid composite membrane loaded with DuPont Krytox 101. The solid-liquid composite membrane was then attached to Emulsifier 1 and poured into the same mixed emulsion in the same manner as in Example 15. The transmembrane pressure difference of the emulsion was tested throughout the entire process. The test results are shown in Figure 9 (corresponding to the curve for the solid-liquid composite membrane pre-loaded with the functional liquid). The transmembrane pressure difference of the solid-liquid composite membrane pre-loaded with the functional liquid was 42.3 kPa.

[0101] As can be seen from the comparison between Example 15 and Comparative Example 1, the in situ formed hierarchical porous aerogel-based confined liquid membrane provided by the present application has a greater drag reduction effect than a solid-liquid composite membrane preloaded with a functional liquid.

[0102] Example 16 This example provides a membrane emulsification method. The emulsification apparatus 1 in Figure 9 was used, which had a channel 10 and an aerogel thin film 12, in which the aerogel thin film 12 was a circular plate with a diameter of 25 mm cut out from the hierarchical porous aerogel thin film prepared in Example 13 of the present application. A homogeneous premix emulsion was prepared, which consisted of cyclohexane and deionized water in a volume ratio of 2:1, containing 1% AKY by mass. A uniform mixed emulsion is injected into the channel 10 at a pressure of 45 kPa and a fixed flow rate of 3 ml / min, and the mixed emulsion passes through the aerogel thin film 12 to obtain an emulsion 13 . Optical microscope photographs of the mixed emulsion before emulsification and the emulsion after membrane emulsification in this example are shown in Figure 11a, particle size distribution diagrams of the emulsion before and after emulsification are shown in Figure 12 (1% in Figure 12 corresponds to the particle size distribution before emulsification, and ME-1% corresponds to the particle size distribution after emulsification), and particle size statistics diagrams are shown in Figure 13 (1%, corresponding to M1). As can be seen from Figures 11, 12, and 13, the emulsions prepared using the hierarchical porous aerogel thin film of this application have good uniformity.

[0103] Example 17 Unlike Example 16, in Example 17, the volume ratio of cyclohexane to deionized water in the premixed emulsion of Example 17 was 2:1, and it contained 2% AKY by mass. Optical microscope photographs of the mixed emulsion before emulsification and after membrane emulsification in this example are shown in Figure 11b, particle size distribution diagrams of the emulsion before and after emulsification are shown in Figure 12 (2% in Figure 12 corresponds to the particle size distribution before emulsification, and ME-2% corresponds to the particle size distribution after emulsification), and particle size statistics diagrams are shown in Figure 13 (2%, corresponding to M2). As can be seen from Figures 11, 12, and 13, the emulsions prepared using the hierarchical porous aerogel thin film of this application have good uniformity.

[0104] Example 18 Unlike Example 16, in Example 18, the volume ratio of cyclohexane to deionized water in the premixed emulsion of Example 18 was 2:1, and it contained 3% AKY by mass.

[0105] Optical microscope photographs of the mixed emulsion before emulsification and after membrane emulsification in this example are shown in Figure 11c, particle size distribution diagrams of the emulsion before and after emulsification are shown in Figure 12 (3% in Figure 12 corresponds to the particle size distribution before emulsification, and ME-3% corresponds to the particle size distribution after emulsification), and particle size statistics diagrams are shown in Figure 13 (3%, corresponding to M3). As can be seen from Figures 11, 12, and 13, the emulsions prepared using the hierarchical porous aerogel thin film of this application have good uniformity.

[0106] Example 19 Unlike Example 16, in Example 19, the volume ratio of cyclohexane to deionized water in the premixed emulsion of Example 19 is 2:1, and it contains 4% AKY by mass.

[0107] Optical microscope photographs of the mixed emulsion before emulsification and after membrane emulsification in this example are shown in Figure 11d, particle size distribution diagrams of the emulsion before and after emulsification are shown in Figure 12 (4% in Figure 12 corresponds to the particle size distribution before emulsification, and ME-4% corresponds to the particle size distribution after emulsification), and particle size statistics diagrams are shown in Figure 13 (4%, corresponding to M4). As can be seen from Figures 11, 12, and 13, the emulsions prepared using the hierarchical porous aerogel thin film of this application have good uniformity.

[0108] Example 20 Unlike Example 16, in Example 20, the volume ratio of cyclohexane to deionized water in the premixed emulsion of Example 20 is 2:1, and it contains 5% AKY by mass.

[0109] Optical microscope photographs of the mixed emulsion before emulsification and after membrane emulsification in this example are shown in Figure 11e, particle size distribution diagrams of the emulsion before and after emulsification are shown in Figure 12 (5% in Figure 12 corresponds to the particle size distribution before emulsification, and ME-5% corresponds to the particle size distribution after emulsification), and particle size statistics diagrams are shown in Figure 13 (5%, corresponding to M5). As can be seen from Figures 11, 12, and 13, the emulsions prepared using the hierarchical porous aerogel thin film of this application have good uniformity.

[0110] As can be seen from Examples 16 and 17 above, the emulsion size prepared by pre-mixing membrane emulsification using the hierarchical porous aerogel thin film of the present application is very uniform, and the emulsion size can be reduced to about 1 / 18.

[0111] Example 21 This example provides a direct membrane emulsification method using a two-layer thin film assembly. The emulsification apparatus 2 in Figure 14 includes a channel 15, a two-layered thin film assembly 18, and a container 14. The two-layered thin film assembly 18 is configured as follows: The hierarchical porous aerogel thin film prepared in Example 13 of the present application is cut to form first and second circular plates with a diameter of 25 mm. The first and second circular plates are stacked, with the submicron-sized channels of the first circular plate adjacent to the micron-sized channels of the second circular plate. The container 14 contains a continuous phase 17, which is a deionized aqueous solution containing 5% AKY by mass. The two-layered thin film assembly 18 is attached between the outlet end of the channel 15 and the inlet end of the container 14, with the micron-sized channels of the first circular plate adjacent to the outlet end of the channel 15 and the submicron-sized channels of the second circular plate adjacent to the inlet end of the container 14. This installation method results in a smaller transmembrane pressure difference, resulting in benefits such as energy saving and reduced drag.

[0112] Dispersed phase 19 (hexadecane in this example) is injected into channel 15 at a pressure of 30 kPa and a fixed flow rate of 2 ml / min, passes through the two-layer membrane element, and then is transferred to continuous phase 17 to form multiple emulsion 16. The resulting multiple emulsion 16 has a water-in-oil structure, and the structure is shown in FIG.

[0113] Example 22 This example provides a method for emulsion separation, which is shown in Figure 1c. The hierarchical porous aerogel thin film of Example 13 was cut into a disk with a diameter of 35 mm. 30 ml of cyclohexane, 10 ml of deionized water, and 2 g of oleyl polyether-10 carboxylic acid were mixed and stirred uniformly to form a stable mixed emulsion. 0.02 g of oil dye Sudan III was added to dye the cyclohexane. Using a pump device under a pressure of -0.09 MPa, emulsion separation was performed by placing the mixed emulsion at the positive pressure end, and the separation efficiency was calculated by analyzing the components in the separated sample.

[0114] Figure 16 shows optical photographs of emulsion separation before and after the above method, and Figure 17 shows the UV-NIR spectra before and after emulsion separation using the above method. As can be seen from Figures 16 and 17, the hierarchical porous aerogel thin film provided by the present application exhibits excellent separation performance, resulting in a clear solution after separation, changing from a red, turbid solution. Figure 18 shows the Fourier infrared spectra of emulsion separation using the above method before and after. The first, second, and third spectra (from top to bottom) are the standard Fourier infrared characteristic peaks of the emulsifier, cyclohexane, and deionized water, respectively. The fourth and fifth spectra (from top to bottom) in Figure 18 are the infrared spectra of the emulsion before separation and the solution after separation, respectively. As can be seen from the comparison, the emulsion before separation exhibits characteristic peaks of water, cyclohexane, and surface emulsifier, while the solution after separation only exhibits the characteristic peak of deionized water. This indicates that the hierarchical porous aerogel thin film provided by the present application has a good emulsion separation effect, and from the ultraviolet-near-infrared spectrum in Figure 17, it can be estimated that the oil-water separation efficiency of the film is greater than 99%.

[0115] Furthermore, the hierarchical porous aerogel thin film prepared in this application was tested for membrane flow rate, transmembrane pressure difference, hydrophilicity / lipophilicity, and emulsification effect. 1. Membrane flux Membrane flux is used to characterize the rate at which a membrane material filters a liquid, and is usually expressed as the volume of permeate passing through a unit membrane area per unit time at constant pressure and temperature. J=V / At In the formula, V is the volume of the permeate (unit: L), and A is the effective area of ​​the membrane (unit: m 2 ), t is the test time (unit: h), and J is the membrane flux (unit: L / (M 2 ·h)).

[0116] The hierarchical porous aerogel thin film prepared in Example 11 was tested. The membrane diameter was 25 mm, the experimental solution was emulsion (dimethylsilane: deionized water: oleyl polyether ~ 10 carboxylic acid = 1:3:0.04), the feed rate was 3 ml / min, the test time was 14 min, and the volume of the permeated emulsion was 16 ml. The test results showed that the membrane flux J of the emulsion passing through the hierarchical porous aerogel thin film was 511.03 L / (m 2 ·h).

[0117] A control test was conducted using a hierarchical porous aerogel thin film pre-loaded with the functional liquid perfluoropolyether lubricant DuPont Krytox 101. First, a cut-out of the hierarchical porous aerogel thin film prepared in Example 11 was immersed in the functional liquid perfluoropolyether lubricant DuPont Krytox 101 to obtain a hierarchical porous aerogel-based liquid membrane loaded with DuPont Krytox 101. The membrane flux of the thin film pre-loaded with perfluoropolyether oil K101 was tested in the same manner as above, and the membrane flux J through the emulsion was found to be 139.76 L / (m 2 ·h).

[0118] 2. Pressure difference test for emulsion passing through membrane The pressure difference across the emulsion membrane was tested using a pressure sensor (PX2300-10BDI). The hierarchical porous aerogel thin film prepared in Example 6 was cut into 25 mm diameter disks using a laser cutter. A random sample was pre-soaked in the functional liquid perfluoropolyether oil K101 as a control. The transmembrane pressure difference across the emulsion was tested for both the hierarchical porous aerogel thin film sample and the solid-liquid composite membrane loaded with functional liquid K101. The results are shown in Figure 9.

[0119] 3. Hydrophilicity and lipophilicity test The hierarchical porous aerogel thin film of Example 10 was cut into a rectangular piece measuring 4 cm in length and 1 cm in width, and the contact angle of the film with cyclohexane in air was tested using a video optical contact angle meter. The test results are shown in Figure 18, which indicate that the hierarchical porous aerogel thin film is superphilic to cyclohexane in air, i.e., it exhibits superoleophilicity in air.

[0120] The same hierarchical porous aerogel thin film was attached to a transparent cuvette, and deionized water was poured into the transparent cuvette to test the contact angle of the liquid film formed in situ in water with cyclohexane. The test results are shown in Figure 18, which indicate that the liquid film formed in situ in water exhibits the properties of superoleophobic cyclohexane, i.e., it exhibits superoleophobicity in water.

[0121] 4. Emulsification index test Emulsions were prepared using the hierarchical porous aerogel thin films in Examples 7, 8, 9, and 10. (The preparation process was the same as in Example 16, with the only difference being that different thin films were used as test subjects and homogeneous mixed solutions containing different concentrations of AKY were used.) The resulting emulsions were allowed to stand at room temperature for three weeks, after which the volume of the emulsion layer and the total volume of the sample were measured. The emulsification index was calculated according to the following formula: Creaming index=(h e / h t )100% where h e is the volume of the emulsion layer, and h t is the total volume of the sample. Emulsion partitioning refers to the separation of the water / oil phase, a phenomenon in which the emulsion becomes unstable. The higher the emulsification index, the greater the proportion of the emulsion layer in the total sample volume, and the more stable the emulsion. The calculated results are shown in Table 1.

[0122] [Table 1]

[0123] 5. Stability of the prepared emulsion and membrane emulsification cycle stability test The microemulsion prepared in Example 18 was sampled every week and observed under an optical microscope. The emulsion particle size was then statistically analyzed using ImageJ. The same membrane was emulsified three times, and the emulsion particle size was used to measure the membrane emulsification stability. The statistical analysis structure is shown in Figure 20.

[0124] In summary, this application describes the preparation of hierarchical porous aerogel thin films by adding a hydrophilic polymer additive to the nanofiber deprotonation process, which induces transient phase separation during the sol-gel process. These hierarchical porous aerogel thin films provide abundant domain-confined spaces for liquids at the micron, submicron, and nanometer scales for membrane emulsification and emulsion separation, allowing for in situ liquid membrane formation, stimuli-responsiveness, and diverse performance. These hierarchical porous aerogel-based liquid membranes offer reduced drag, energy savings, good antifouling properties, and excellent emulsification and emulsion separation efficiencies. The preparation method for hierarchical porous aerogel thin films provided by this application is simple, has a short cycle time, and is suitable for industrial mass production, laying a good foundation for the application of aerogel thin films in membrane emulsification and membrane separation.

[0125] Each aspect, embodiment, feature, and example of the present application is to be considered in all respects as illustrative and not intended as limiting of the present application, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the present application as claimed.

[0126] Furthermore, the inventors of the present application have conducted tests using other raw materials, process operations, and process conditions described herein with reference to the above examples, and have obtained relatively ideal results.

[0127] While the present application has been described with reference to illustrative embodiments, those skilled in the art should recognize that other changes, omissions, and / or additions may be made, and elements of the embodiments may be substituted with other substantial equivalents, without departing from the spirit and scope of the present application. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present application without departing from the scope of the present application. Therefore, it is not intended herein to limit the present application to the particular embodiments disclosed for carrying out the present application; rather, the present application is intended to include all embodiments falling within the scope of the appended claims. Furthermore, unless otherwise specified, the terms first, second, etc. do not denote any order or importance, and terms such as first, second, etc. are used to distinguish one element from another.

[0128] (Addendum) (Appendix 1) A hierarchical porous aerogel thin film, wherein micron-sized pores are distributed on the surface of the hierarchical porous aerogel thin film, micron-sized channels, submicron-sized channels, and nano-sized three-dimensional network mesopores are distributed inside the hierarchical porous aerogel thin film, and pores corresponding to the micron-sized channels, submicron-sized channels, and nano-sized three-dimensional network mesopores are simultaneously distributed on the cross section of the hierarchical porous aerogel thin film. A hierarchical porous aerogel thin film characterized by:

[0129] (Appendix 2) The micron-sized pores have a pore size of 20 to 80 μm, and / or the micron-sized channels have a diameter of 20 to 50 μm, and / or the submicron-sized channels have a diameter of 2 to 20 μm, and / or the nano-sized three-dimensional network mesopores have a pore size of less than 50 nm; and / or the micron-sized channels and submicron-sized channels are vertical channels, preferably vertical channels perpendicular or nearly perpendicular to the membrane surface, and the micron-sized channels and submicron-sized channels are arranged hierarchically in the thickness direction of the membrane; and / or the hierarchical pores of the hierarchical porous aerogel thin film are nano-sized three-dimensional network mesopores obtained by transient phase separation between Kevlar® nanofibers and a pore-forming polymer, followed by sol-gel conversion, solvent exchange, and drying treatment, and the polymer preferably includes at least one of polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone, more preferably polyvinylpyrrolidone; and / or the pore area ratios of the three types of pores corresponding to the micron-sized channels, the submicron-sized channels, and the nano-sized three-dimensional network mesopores are 2 to 5%, 40 to 65%, and 30 to 68%, respectively; and / or the hierarchical porous aerogel thin film has superhydrophilicity and superoleophilicity in air; 2. The hierarchical porous aerogel thin film according to claim 1,

[0130] (Appendix 3) applying a cast film solution containing Kevlar® nanofibers and a high molecular weight polymer onto a substrate and then transferring it to a solidification bath to form a hierarchical porous hydrogel thin film; and subjecting the hierarchical porous hydrogel thin film to a solvent exchange treatment and drying treatment to obtain a hierarchical porous aerogel thin film. A method for preparing a hierarchical porous aerogel thin film.

[0131] (Appendix 4) Specifically, the method for applying the cast film solution onto a substrate includes a single-layer substrate method, which includes applying the cast film solution onto at least one surface of a substrate; Preferably, in the cast film solution, the mass ratio of Kevlar (registered trademark) nanofiber to the polymer is 4:1 to 1:2; and / or the fiber size of the Kevlar (registered trademark) nanofiber is 200D to 1000D; and / or the polymer comprises at least one of polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone, preferably polyvinylpyrrolidone, more preferably an average molecular weight of the polyvinylpyrrolidone is 8 kDa to 1300 kDa; and / or the method for preparing the cast film solution specifically includes the steps of uniformly dispersing Kevlar® fibers, an alkali modifier, and a viscosity reducer in dimethyl sulfoxide to obtain a Kevlar® nanofiber dispersion, and adding the polymer to the Kevlar® nanofiber dispersion to obtain the cast film solution; Preferably, the concentration of Kevlar (registered trademark) nanofibers in the Kevlar (registered trademark) nanofiber dispersion is 1 to 3 wt%, and / or the alkaline modifier includes potassium tert-butoxide and / or potassium hydroxide, and / or the viscosity reducer includes methanol and / or ethanol, and / or the mass ratio of Kevlar (registered trademark) fibers, alkaline modifier, and viscosity reducer in the Kevlar (registered trademark) nanofiber dispersion is 1:1:1 to 2:2:1, and / or the preparation method specifically includes a step of applying the cast film solution onto a substrate using a squeegee application method, and preferably, the speed of the squeegee application method is 5-10 mm / s, and / or the spin coating time is 5-15 s, and / or the distance between the squeegee and the substrate is 250-1000 μm; and / or the substrate comprises glass and / or aluminum foil; and / or the solidification bath contains water or a combination of water and ethanol, preferably, when the solidification bath contains water and ethanol, the volume ratio of water to ethanol is 5:1 to 1:1, more preferably 2:1 to 1:1; and / or the temperature of the solidification bath is 0 to 20°C; and / or the solvent exchange treatment employs a mixed solution of tert-butanol and water, preferably with a volume ratio of tert-butanol to water of 1:1 to 1:4; and / or the drying treatment includes freeze-drying and / or supercritical drying, preferably the drying treatment includes freeze-drying, more preferably the freeze-drying includes continuous drying for 4 to 6 hours under temperature conditions of -40 to -100°C and atmospheric pressure conditions of 5 to 100 kPa; 4. The method of claim 3,

[0132] (Appendix 5) The preparation method includes adjusting the number, pore size, and distribution of micron-sized pores in the hierarchical porous aerogel thin film by adjusting at least one of the mass ratio of Kevlar® nanofibers and high molecular weight polymer in the cast film solution, the solvent content of the cast film solution, the temperature of the solidification bath, the composition of the solidification bath, and the molecular weight of the high molecular weight polymer, thereby adjusting the morphology, number, and distribution of micron-sized channels and submicron-sized channels. 5. The method of claim 3 or 4.

[0133] (Appendix 6) A hierarchical porous aerogel thin film obtained by the preparation method described in any one of Appendixes 3 to 5.

[0134] (Appendix 7) A hierarchical porous aerogel thin film according to any one of claims 1, 2, and 6, and a liquid infiltrating and filling the hierarchical porous aerogel thin film. A hierarchical porous aerogel-based in situ confined liquid membrane characterized by:

[0135] (Appendix 8) The hierarchical porous aerogel-based in-situ confined liquid membrane is formed in-situ during a membrane emulsification or emulsion separation process by filling a membrane emulsification sample or emulsion separation sample into the hierarchical porous aerogel thin film as the sample passes through the membrane emulsification or emulsion separation process; and / or the hierarchical porous aerogel-based in situ confined liquid membrane can switch between membrane emulsification and emulsion separation functions depending on the difference in sample injection pressure and / or injection flow rate; and / or, when the sample injection pressure is 30-45 kPa and / or the injection rate is 1 ml / min-3 ml / min, the hierarchical porous aerogel-based in-situ confinement liquid membrane has at least a membrane emulsification function, and when the sample injection pressure is -0.09--0.1 MPa and / or the injection rate is 0.1 ml / min-0.3 ml / min, the hierarchical porous aerogel-based in-situ confinement liquid membrane has at least an emulsion separation function; and / or the hierarchical porous aerogel-based in situ confined liquid film has superoleophobicity underwater. 8. The hierarchical porous aerogel-based in situ confined liquid membrane of claim 7.

[0136] (Appendix 9) Application of the hierarchical porous aerogel thin film described in any one of Supplementary Notes 1, 2, and 6 or the hierarchical porous aerogel-based in situ confined liquid membrane described in any one of Supplementary Notes 7 and 8 in membrane emulsification and / or emulsion separation.

[0137] (Appendix 10) 10. The hierarchical porous aerogel thin film according to claim 1, 2, or 6, comprising multiple layers. 10. A thin film assembly comprising:

[0138] (Appendix 11) The thin film assembly includes a plurality of the hierarchical porous aerogel thin films stacked together, the hierarchical porous aerogel thin films having longitudinal channels; Preferably, in the thin film assembly, the micron-sized channels in one hierarchical porous aerogel thin film are adjacent to the submicron-sized channels in another adjacent hierarchical porous aerogel thin film; More preferably, the thin film assembly has a two-layer structure, and the micron-sized channels of the first layered porous aerogel thin film are adjacent to the submicron-sized channels of the second layered porous aerogel thin film. 11. The thin film assembly of claim 10.

[0139] (Appendix 12) Direct membrane emulsification or premix membrane emulsification, The direct membrane emulsification method includes passing a dispersed phase through the hierarchical porous aerogel thin film according to any one of Supplementary Notes 1, 2, and 6 or the thin film assembly according to any one of Supplementary Notes 10 and 11, and then through a continuous phase under conditions of a pressure of 30 to 45 kPa and / or an injection rate of 1 ml / min to 3 ml / min, to obtain an emulsion; The premixing membrane emulsification method includes passing a uniform premixed emulsion containing an oil phase, an aqueous phase, and an emulsifier through the hierarchical porous aerogel thin film according to any one of Supplementary Notes 1, 2, and 6 or the thin film assembly according to any one of Supplementary Notes 10 and 11 under conditions of a pressure of 30 to 45 kPa and / or an injection rate of 1 ml / min to 3 ml / min to obtain an emulsion. A membrane emulsification method characterized by:

[0140] (Appendix 13) The dispersed phase in the direct membrane emulsification method and the oil phase in the premix membrane emulsification method are water-insoluble organic substances, and preferably contain at least one of dodecane, hexadecane, cyclohexane, mineral oil, paraffin, and dimethylsilane, more preferably at least one of dodecane, hexadecane, and cyclohexane; and / or, in the premixed emulsion, the volume ratio of the oil phase to the water phase is 1:3 to 3:1; and / or, in the pre-mix membrane emulsification method, the emulsifier comprises at least one of oleyl polyether-10 carboxylic acid, Tween 80, Tween 85, Span 80, Span 85, and sodium dodecyl sulfate, preferably oleyl polyether-10 carboxylic acid; and / or the content of the emulsifier is 1% to 5% of the total mass of the premixed emulsion; and / or, in the direct membrane emulsification method, the dispersed phase is passed through the thin film assembly and then passed through a mixed solution containing a continuous phase and a surfactant, the surfactant comprising at least one of oleyl polyether-10 carboxylic acid, Tween 80, Tween 85, Span 80, Span 85 and sodium dodecyl sulfate, preferably oleyl polyether-10 carboxylic acid; and / or the emulsion obtained by the membrane emulsification is an oil-in-water emulsion and / or a water-in-oil emulsion; and / or the size distribution of the emulsion obtained by the membrane emulsification method is 0 to 10 μm; And / or, the creaming index of the emulsion obtained by the membrane emulsification method is 54.7% to 78.8%. 13. The membrane emulsification method according to claim 12,

[0141] (Appendix 14) Passing the sample to be separated through the hierarchical porous aerogel thin film according to any one of Supplementary Notes 1, 2, and 6 or the thin film assembly according to any one of Supplementary Notes 10 and 11 under the action of a pressure of -0.09 to -0.1 MPa and / or an injection rate of 0.1 ml / min to 0.3 ml / min to achieve emulsion separation; Preferably, the oil-water separation efficiency of the emulsion separation method is greater than 99%. 1. A method for separating an emulsion, comprising:

[0142] (Appendix 15) a liquid inlet channel, a membrane unit, and a driving mechanism, wherein the membrane unit comprises the hierarchical porous aerogel thin film described in any one of Supplementary Notes 1, 2, and 6 or the thin film assembly described in any one of Supplementary Notes 10 and 11, one end of the liquid inlet channel communicates with the membrane unit, and a sample to be emulsified is injected into the liquid inlet channel under the action of the driving mechanism to flow into the membrane unit and perform emulsification; Preferably, the membrane unit includes a thin film assembly having a two-layer membrane structure as described in Supplementary Note 14, i.e., the micron-sized channels of the first layered porous aerogel thin film of the thin film assembly having a two-layer membrane structure are arranged adjacent to the submicron-sized channels of the second layered porous aerogel thin film, and the second layered porous aerogel thin film is arranged adjacent to the liquid inlet channel, so that the sample to be emulsified first flows into the thin film assembly in a direction passing through the micron-sized channels of the second layered porous aerogel thin film. An emulsification device characterized by:

Claims

1. A hierarchical porous aerogel thin film, wherein micron-sized pores are distributed on the surface of the hierarchical porous aerogel thin film, micron-sized channels, submicron-sized channels, and nano-sized three-dimensional network mesopores are distributed inside the hierarchical porous aerogel thin film, and pores corresponding to the micron-sized channels, submicron-sized channels, and nano-sized three-dimensional network mesopores are simultaneously distributed on the cross section of the hierarchical porous aerogel thin film. A hierarchical porous aerogel thin film characterized by:

2. The micron-sized pores have a pore size of 20 to 80 μm, and / or the micron-sized channels have a diameter of 20 to 50 μm, and / or the submicron-sized channels have a diameter of 2 to 20 μm, and / or the nano-sized three-dimensional network mesopores have a pore size of less than 50 nm; and / or the micron-sized channels and submicron-sized channels are vertical channels, preferably vertical channels perpendicular or nearly perpendicular to the membrane surface, and the micron-sized channels and submicron-sized channels are arranged hierarchically in the thickness direction of the membrane; and / or the hierarchical pores of the hierarchical porous aerogel thin film are nano-sized three-dimensional network mesopores obtained by transient phase separation between Kevlar (registered trademark) nanofibers and a pore-forming polymer, followed by sol-gel conversion, solvent exchange, and drying treatment, and the polymer preferably includes at least one of polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone, more preferably polyvinylpyrrolidone; and / or the pore area ratios of the three types of pores corresponding to the micron-sized channels, the submicron-sized channels, and the nano-sized three-dimensional network mesopores are 2 to 5%, 40 to 65%, and 30 to 68%, respectively; and / or the hierarchical porous aerogel thin film has superhydrophilicity and superoleophilicity in air. The hierarchical porous aerogel thin film according to claim 1 .

3. applying a cast film solution containing Kevlar® nanofibers and a high molecular weight polymer onto a substrate and then transferring it to a solidification bath to form a hierarchical porous hydrogel thin film; and subjecting the hierarchical porous hydrogel thin film to a solvent exchange treatment and drying treatment to obtain a hierarchical porous aerogel thin film. A method for preparing a hierarchical porous aerogel thin film.

4. Specifically, the method for applying the cast film solution onto a substrate includes a single-layer substrate method, which includes applying the cast film solution onto at least one surface of a substrate; Preferably, in the cast film solution, the mass ratio of Kevlar® nanofiber to high molecular weight polymer is 4:1 to 1:2; and / or the fiber size of the Kevlar nanofiber is 200D to 1000D; and / or the polymer comprises at least one of polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone, preferably polyvinylpyrrolidone, more preferably the average molecular weight of the polyvinylpyrrolidone is 8 kDa to 1300 kDa; and / or the method for preparing the cast film solution specifically includes the steps of uniformly dispersing Kevlar® fibers, an alkali modifier, and a viscosity reducer in dimethyl sulfoxide to obtain a Kevlar® nanofiber dispersion, and adding the polymer to the Kevlar® nanofiber dispersion to obtain the cast film solution; Preferably, the concentration of Kevlar® nanofibers in the Kevlar® nanofiber dispersion is 1 to 3 wt %, and / or the alkaline modifier comprises potassium tert-butoxide and / or potassium hydroxide, and / or the viscosity reducing agent comprises methanol and / or ethanol, and / or the mass ratio of Kevlar® fibers, alkaline modifier, and viscosity reducing agent in the Kevlar® nanofiber dispersion is 1:1:1 to 2:2:1; and / or the preparation method specifically includes a step of applying the cast film solution onto a substrate using a squeegee application method, and preferably, the speed of the squeegee application method is 5-10 mm / s, and / or the spin coating time is 5-15 s, and / or the distance between the squeegee and the substrate is 250-1000 μm; and / or the substrate comprises glass and / or aluminum foil; and / or the solidification bath comprises water or a combination of water and ethanol, preferably, when the solidification bath comprises water and ethanol, the volume ratio of water to ethanol is between 5:1 and 1:1, more preferably between 2:1 and 1:1; and / or the temperature of the solidification bath is 0 to 20°C; and / or the solvent exchange treatment employs a mixed solution of tert-butanol and water, preferably with a volume ratio of tert-butanol to water of 1:1 to 1:4; and / or the drying treatment includes freeze-drying and / or supercritical drying, preferably the drying treatment includes freeze-drying, more preferably the freeze-drying includes continuous drying for 4 to 6 hours at a temperature of -40 to -100°C and an atmospheric pressure of 5 to 100 kPa; 4. The method of claim 3.

5. The preparation method includes adjusting the number, pore size, and distribution of micron-sized pores in the hierarchical porous aerogel thin film by adjusting at least one of the mass ratio of Kevlar® nanofibers and high molecular weight polymer in the cast film solution, the solvent content of the cast film solution, the temperature of the solidification bath, the composition of the solidification bath, and the molecular weight of the high molecular weight polymer, thereby adjusting the morphology, number, and distribution of micron-sized channels and submicron-sized channels.

5. The method according to claim 3 or 4.

6. A hierarchical porous aerogel thin film obtained by the preparation method according to any one of claims 3 to 5.

7. A method for producing a hierarchical porous aerogel thin film comprising the hierarchical porous aerogel thin film according to any one of claims 1, 2, and 6, and a liquid infiltrating and filling the hierarchical porous aerogel thin film. A hierarchical porous aerogel-based in situ confined liquid membrane characterized by:

8. The hierarchical porous aerogel-based in-situ confined liquid membrane is formed in-situ during a membrane emulsification or emulsion separation process by filling a membrane emulsification sample or emulsion separation sample into the hierarchical porous aerogel thin film as the sample passes through the membrane emulsification or emulsion separation process; and / or the hierarchical porous aerogel-based in situ confined liquid membrane can switch between membrane emulsification and emulsion separation functions depending on the difference in sample injection pressure and / or injection flow rate; and / or, when the sample injection pressure is 30-45 kPa and / or the injection rate is 1 ml / min-3 ml / min, the hierarchical porous aerogel-based in-situ confinement liquid membrane has at least a membrane emulsification function, and when the sample injection pressure is -0.09--0.1 MPa and / or the injection rate is 0.1 ml / min-0.3 ml / min, the hierarchical porous aerogel-based in-situ confinement liquid membrane has at least an emulsion separation function; and / or the hierarchical porous aerogel-based in situ confined liquid film has superoleophobicity underwater. The hierarchical porous aerogel-based in situ confined liquid membrane of claim 7.

9. The application of the hierarchical porous aerogel thin film according to any one of claims 1, 2 and 6 or the hierarchical porous aerogel-based in situ confined liquid membrane according to any one of claims 7 and 8 in membrane emulsification and / or emulsion separation.

10. The hierarchical porous aerogel thin film according to any one of claims 1, 2 and 6, 10. A thin film assembly comprising:

11. The thin film assembly includes a plurality of the hierarchical porous aerogel thin films stacked together, the hierarchical porous aerogel thin films having longitudinal channels; Preferably, in the thin film assembly, the micron-sized channels in one hierarchical porous aerogel thin film are adjacent to the submicron-sized channels in another adjacent hierarchical porous aerogel thin film; More preferably, the thin film assembly has a two-layer structure, and the micron-sized channels of the first layered porous aerogel thin film are adjacent to the submicron-sized channels of the second layered porous aerogel thin film.

11. The membrane assembly of claim 10.

12. Direct membrane emulsification or premix membrane emulsification, The direct membrane emulsification method includes passing a dispersed phase through the hierarchical porous aerogel thin film according to any one of claims 1, 2, and 6 or the thin film assembly according to any one of claims 10 and 11 under conditions of a pressure of 30 to 45 kPa and / or an injection rate of 1 ml / min to 3 ml / min, and then passing the dispersed phase through a continuous phase to obtain an emulsion; The premixing membrane emulsification method includes passing a uniform premixed emulsion containing an oil phase, an aqueous phase, and an emulsifier through the hierarchical porous aerogel thin film according to any one of claims 1, 2, and 6 or the thin film assembly according to any one of claims 10 and 11 under conditions of a pressure of 30 to 45 kPa and / or an injection rate of 1 ml / min to 3 ml / min to obtain an emulsion. A membrane emulsification method characterized by:

13. The dispersed phase in the direct membrane emulsification method and the oil phase in the premix membrane emulsification method are water-insoluble organic substances, and preferably contain at least one of dodecane, hexadecane, cyclohexane, mineral oil, paraffin, and dimethylsilane, more preferably at least one of dodecane, hexadecane, and cyclohexane; and / or, in the premixed emulsion, the volume ratio of the oil phase to the water phase is 1:3 to 3:1; and / or, in the pre-mix membrane emulsification method, the emulsifier comprises at least one of oleyl polyether-10 carboxylic acid, Tween 80, Tween 85, Span 80, Span 85, and sodium dodecyl sulfate, preferably oleyl polyether-10 carboxylic acid; and / or the content of the emulsifier is 1% to 5% of the total mass of the premixed emulsion; and / or, in the direct membrane emulsification method, the dispersed phase is passed through the thin film assembly and then passed through a mixed solution containing a continuous phase and a surfactant, the surfactant comprising at least one of oleyl polyether-10 carboxylic acid, Tween 80, Tween 85, Span 80, Span 85 and sodium dodecyl sulfate, preferably oleyl polyether-10 carboxylic acid; and / or the emulsion obtained by the membrane emulsification is an oil-in-water emulsion and / or a water-in-oil emulsion; and / or the size distribution of the emulsion obtained by the membrane emulsification method is 0 to 10 μm; and / or the creaming index of the emulsion obtained by the membrane emulsification method is 54.7% to 78.8%. The membrane emulsification method according to claim 12.

14. A sample to be separated is passed through the hierarchical porous aerogel thin film according to any one of claims 1, 2 and 6 or the thin film assembly according to any one of claims 10 and 11 under the action of a pressure of -0.09 to -0.1 MPa and / or an injection rate of 0.1 ml / min to 0.3 ml / min to achieve emulsion separation; Preferably, the oil-water separation efficiency of the emulsion separation method is greater than 99%.

1. A method for separating an emulsion, comprising:

15. a liquid inlet channel, a membrane unit, and a driving mechanism, wherein the membrane unit comprises the hierarchical porous aerogel thin film according to any one of claims 1, 2, and 6 or the thin film assembly according to any one of claims 10 and 11, one end of the liquid inlet channel is connected to the membrane unit, and a sample to be emulsified is injected into the liquid inlet channel under the action of the driving mechanism, and flows into the membrane unit to be emulsified; Preferably, the membrane unit includes a thin film assembly having a two-layer membrane structure as described in claim 14, i.e., the micron-sized channels of the first multi-layer porous aerogel thin film of the thin film assembly having a two-layer membrane structure are provided adjacent to the sub-micron-sized channels of the second multi-layer porous aerogel thin film, and the second multi-layer porous aerogel thin film is provided adjacent to the liquid inlet channel, so that the sample to be emulsified first flows into the thin film assembly in a direction passing through the micron-sized channels of the second multi-layer porous aerogel thin film. An emulsification device characterized by:

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