A gel-assisted preparation method of two-sided dura mater, product and application thereof

Abstract

The application discloses a gel-assisted preparation method of a two-faced membrane, a product and application, and the preparation method comprises the following steps: (1) dissolving a polymer in a modified solvent, and then adding a hydrophobic modifier to obtain a mixed homogeneous sol; (2) spreading the sol into a flat liquid film, and cooling to room temperature to obtain a gel; and (3) contacting a surface of a hydrophilic porous membrane material with a surface of the gel, so that the hydrophobic modifier of the gel performs hydrophobic modification on the surface of the hydrophilic porous membrane material, and a one-side hydrophobic modified two-faced membrane material is obtained after separation. The method can be used for one-side hydrophobic modification of a hydrophilic membrane material, that is, the modification area in the transverse direction and the modification thickness in the longitudinal direction are controlled, and the method has the advantages of simplicity and controllability, and can realize large-scale continuous modification.

Description

Technical Field

[0001] This invention relates to the field of unilateral hydrophobic modification technology, and in particular to a gel-assisted method for preparing bifacial membranes, products, and applications. Background Technology

[0002] Janus materials refer to materials with two identical structures but opposite properties. A typical example is a material that is hydrophilic on one side and hydrophobic on the other. Due to its unique asymmetric wettability, it has broad application prospects in fields such as oil-water separation, freshwater collection, sweat management, and wound protection.

[0003] Methods for preparing Janus materials can be divided into two categories: asymmetric preparation and asymmetric modification.

[0004] Asymmetric fabrication refers to the preparation of two materials with opposite properties, which are then bonded together to obtain a Janus structure. For example, Chinese patent document CN110039863B discloses a Janus-type micro / nano composite fiber membrane with one side superhydrophobic and the other side hydrophilic, and its preparation method. This involves preparing micro / nano cellulose acetate (CA) membranes and micro / nano PVDF fiber membranes separately by centrifugal spinning or electrospinning, and then combining the hydrophilic micro / nano CA fiber membrane with the hydrophobic PVDF fiber membrane by hot pressing or bonding. The Janus structure obtained by asymmetric fabrication suffers from insufficient interfacial forces, leading to desorption.

[0005] Asymmetric modification refers to the unilateral modification of homogeneous materials to give the two sides opposite properties, effectively avoiding the problem of insufficient interfacial forces. Methods such as spraying, solution flotation, and plasma modification have been widely used. For example, Yang et al. (Yang HC, Zhong WW, Hou JW, et al. Janus hollow fiber membrane with a mussel-inspired coating on the lumen surface for direct contact membrane distillation[J]. Journal of Membrane Science, 2017, 523: 1-7) reported the application of Janus hollow fiber membrane material in underwater direct contact membrane distillation. A hydrophilic layer of polydopamine / polyethyleneimine is deposited on the inner surface of a hydrophobic polypropylene hollow fiber membrane, and the thickness of the hydrophilic layer can be adjusted by the deposition time.

[0006] However, asymmetric modification techniques suffer from an imbalance. Currently, commercially available thin films are predominantly intrinsically hydrophilic materials, but research on asymmetric modification techniques focuses on hydrophilizing hydrophobic substrates. This situation leads to a significant functional misalignment between the fundamental material properties and the mainstream research direction. This is because surface hydrophobic modification techniques often use organic phases as solvents. The low surface energy of organic solvents makes controllable diffusion in the lateral and longitudinal directions of high surface energy thin film materials difficult, ultimately resulting in overall modification rather than unilateral modification, making the fabrication of Janus structures challenging. Therefore, it is necessary to propose a unilateral hydrophobic modification technique to achieve unilateral hydrophobic construction of hydrophilic materials. Summary of the Invention

[0007] This invention provides a gel-assisted method for preparing bifacial membranes, products, and applications. The method of this invention can be used for unilateral hydrophobic modification of hydrophilic membrane materials, that is, to achieve the modification area in the lateral direction and the control of the modification thickness in the longitudinal direction. It has the advantages of being simple and controllable, and can achieve large-scale continuous modification.

[0008] The technical solution of the present invention is as follows: A gel-assisted method for preparing a bifacial membrane includes the following steps: (1) Dissolve the polymer in a modified solvent, and then add a hydrophobic modifier to obtain a uniformly mixed sol; (2) Spread the sol into a flat liquid film and cool it to room temperature to obtain a gel; (3) The surface of the hydrophilic porous membrane material is brought into contact with the surface of the gel so that the hydrophobic modifier of the gel modifies the surface of the hydrophilic porous membrane material. After separation, a bifacial membrane material with unilateral hydrophobic modification is obtained.

[0009] Preferably, the polymer is a polymer capable of physical or chemical cross-linking, and the molecular weight of the polymer is 100,000 to 400,000.

[0010] A gel refers to a three-dimensional network structure formed by the interconnection of colloidal particles or polymers in a solution under certain conditions, with the solvent serving as the dispersion medium filling the voids within the structure. The medium is enclosed within the cross-linked network and cannot flow freely. This invention utilizes the confinement effect of the polymer network on the dispersion solvent to achieve effective control over the dispersion medium—the modified solvent—and accomplish controllable unilateral hydrophobic modification. The gel-controlled modification mechanism of this invention utilizes the synergistic effect of capillary force and gel osmotic pressure within the pores of the hydrophilic porous membrane to achieve controllable diffusion of the solvent on the surface and inside the pores of the hydrophilic porous membrane, thus realizing unilateral hydrophobic modification and the preparation of Janus structures.

[0011] In this invention, the polymer undergoes physical or chemical cross-linking in a modifying solvent to obtain a gel. The hydrophobic modifier in the gel undergoes dehydration condensation on the surface of the hydrophilic porous membrane material or within the membrane pores, forming a hydrophobic layer, thereby obtaining a unilaterally hydrophobically modified Janus material. This invention utilizes the osmotic pressure of the gel to counteract the capillary force of the liquid within the membrane pores, thereby achieving controlled diffusion of the liquid and realizing the preparation of the Janus structure. The gel-controlled porous material modification strategy of this invention can effectively avoid the uncontrolled diffusion of low surface energy modifying solvents, achieve regioselective modification, and construct various heterostructures to achieve functional integration and functional coupling.

[0012] Preferably, the thickness of the hydrophobic modified layer of the zeta membrane material is controlled by adjusting the pore radius of the hydrophilic porous membrane material, the viscosity of the modified solvent, the hydrophobic modification time, and the concentration of the polymer in the sol.

[0013] Preferably, the thickness of the hydrophobic modified layer of the two-sided membrane material is... Calculated by the following formula: In the formula, The pore radius of the hydrophilic porous membrane material; The viscosity of the modified solvent; For capillary force; Osmotic pressure, For modification time; Among them, capillary force The calculation formula is: In the formula, The surface tension coefficient of the modified solvent; The contact angle of the modified solvent on the surface of the hydrophilic porous membrane material; osmotic pressure The calculation formula is: In the formula, It is a constant (≈1.1). It is a simplified concentration. ≈0.588.

[0014] Reduced concentration is used to describe the crowding of polymer chains in solution and is defined as the actual concentration of the polymer chains. Its overlapping concentration The ratio: .

[0015] Preferably, the polymer is a block copolymer; the block copolymer is at least one of polystyrene-polyisoprene-polystyrene, polystyrene-polybutadiene-polystyrene, polystyrene-polyethylene glycol-polystyrene, and polystyrene-polysiloxane-polystyrene.

[0016] Preferably, the melting point of the modified solvent is 0 to 20°C. o C, Flash point 100 o C and above.

[0017] More preferably, the modified solvent is hexadecane and / or tetradecane.

[0018] Preferably, the hydrophobic modifier is at least one of chlorosilane, fluorochlorosilane, and fluorosiloxane.

[0019] More preferably, the hydrophobic modifier is at least one selected from octadecyltrichlorosilane, hexadecyltrichlorosilane, tetradecyltrichlorosilane, dodecyltrichlorosilane, 1H,1H,2H,2H-perfluorooctyltrichlorosilane, 1H,1H,2H,2H-perfluorodecyltrichlorosilane, 1H,1H,2H,2H-perfluorohexyltrichlorosilane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, 1H,1H,2H,2H-perfluorohexyltriethoxysilane, 1H,1H,2H,2H-perfluorohexyltrimethoxysilane, 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, and 1H,1H,2H,2H-perfluorodecyltrimethoxysilane.

[0020] Preferably, in the sol, the polymer concentration is 5~25 wt% and the hydrophobic modifier concentration is 0.5~50 μL / g.

[0021] Preferably, in step (1), the dissolution temperature of the polymer in the modified solvent is between 100 and 120 °C. o C; Dissolution time is 1.5~3 h.

[0022] Preferably, the hydrophilic porous membrane material is a ceramic membrane made of one or more of Al2O3, SiO2, MgO, ZrO2, and TiO2; or a polymer membrane made of one or more of nitrocellulose, cellulose acetate, mixed cellulose, ethylcellulose, polysulfone, polyethersulfone, polyamide, polysulfoneamine, polyethylene, polypropylene, polyvinyl chloride, polycarbonate, polytetraethylene, and polyvinylidene ethylene; or a mixed porous membrane made of the above materials.

[0023] Preferably, the hydrophilic porous membrane material has a pore size of 20 nm to 100 μm, a thickness of 50 to 500 μm, and a porosity of 50 to 80%.

[0024] Preferably, step (2) includes: coating the sol onto the surface of the uniformly driven transmission mechanism to form a smooth liquid film, cooling it to room temperature, and obtaining a smooth and continuously driven gel.

[0025] Preferably, the transmission mechanism is a conveyor belt or roller; the material of the transmission mechanism is polymer, glass, ceramic or metal.

[0026] The sol can be spread into a smooth liquid film by roller coating or scraper coating.

[0027] Preferably, step (3) includes: contacting the surface of the hydrophilic porous membrane material with the surface of the gel through an unwinding device, so that the hydrophobic modifier of the gel modifies the surface of the hydrophilic porous membrane material hydrophobically, drying the hydrophilic porous membrane material after separation, and winding it up through a winding device to obtain a Janus material with hydrophobic modification on one side.

[0028] The hydrophilic porous membrane material moves in the same direction and at the same speed as the gel on the surface of the transport mechanism.

[0029] Preferably, in step (3), the contact reaction time between the surface of the hydrophilic porous membrane material and the surface of the gel is 10~80 s.

[0030] The present invention also provides a bifacial membrane material prepared by the preparation method described above.

[0031] The present invention also provides the application of the aforementioned bifacial membrane material in directional transport, oil-water separation, or membrane distillation.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention utilizes the synergistic effect of capillary force and gel osmotic pressure on the modified solvent inside the hydrophilic porous membrane channel to effectively control the controllable diffusion of the modified solvent and the hydrophobic modifier in the modified solvent in the membrane thickness direction, thereby achieving unilateral hydrophobic modification.

[0033] (2) The present invention can adjust the osmotic pressure of the gel by adjusting the polymer concentration, thereby achieving precise control of unilateral hydrophobic modification.

[0034] (3) Due to the fluidity of the sol and the flexibility and elasticity of the gel, the method of the present invention has excellent potential for large-scale preparation.

[0035] (4) Due to the diversity of hydrophobic modifiers and their strong reactivity, the method of the present invention can achieve unilateral hydrophobic modification of various hydrophilic materials.

[0036] (5) By physically restricting the reaction area and effectively controlling solvent diffusion, this invention can customize various heterogeneous structures to achieve functional integration and application expansion of materials. Attached Figure Description

[0037] Figure 1 A schematic diagram of a large-scale continuous preparation device for gel-controlled regional selective modification of porous materials.

[0038] Figure 2 The results show the thicknesses of different hydrophobic modified layers obtained using laser confocal microscopy. a) is a ceramic film, and b) is a polymer film - polyethersulfone. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments described below are intended to facilitate the understanding of the present invention and do not limit it in any way.

[0040] In the specific implementation method, the selected preparation device is as follows: Figure 1 As shown, it includes an unwinding and rewinding device, a coating device, a material conveying device, a track device, a drying device, and a recycling and replenishment device.

[0041] The unwinding and rewinding devices are used to convey and rewind flexible hydrophilic porous membrane materials at a specified speed.

[0042] The scraping device consists of a liquid bar and a scraper, and is used to obtain a smooth oleogel.

[0043] The tracked device is used to transport oil gel at a specified speed.

[0044] The material conveying device conveys flexible hydrophilic porous membrane material at the same speed as the tracked device.

[0045] The drying device is used to evaporate the residual organic solvent in the flexible hydrophilic porous membrane material to obtain a regionally selectively modified porous material.

[0046] The recycling and replenishment device is used to heat the damaged and modified gel into a sol, and replenish the polymer and modifier to re-gel it.

[0047] The coating device consists of a liquid tank and a scraper. Both are positioned above the tracked device, and the distance between them is adjustable.

[0048] The preparation method includes: firstly, dissolving the block copolymer in an organic solvent at a certain mass concentration at high temperature; after complete dissolution, adding a hydrophobic modifier to obtain a modified solution. The modified solution is then spread onto a continuously moving tracked device, and a scraping device is used to smooth the sol film and cool it into a gel. A material conveying device continuously transports the hydrophilic porous membrane material at the same conveying speed as the tracked device. After maintaining pressureless contact between the hydrophilic porous membrane material and the gel for a period of time, the conveying device continues to transport the hydrophilic porous membrane material into a drying device to remove residual organic solvents, resulting in a unilaterally hydrophobically modified hydrophilic porous membrane material. After drying, the material is wound into a roll by a winding device for later use. The tracked device continues to transport the gel forward and heats it to a sol state before it enters a recycling and replenishment device. Block copolymers, organic solvents, and hydrophobic modifiers are added, and the solution is then transported to a feed tank for secondary gelation.

[0049] The unilateral hydrophobic modification method of this invention is used in the field of Janus structure fabrication, and the modification thickness H is calculated by the following formula: In the formula, The pore radius of the hydrophilic porous material. To modify the solvent viscosity, For capillary force, Osmotic pressure, For modification time; Among them, capillary force The calculation formula is: In the formula, The surface tension coefficient of the modified solvent. The contact angle of the modified solvent on the surface of the hydrophilic material; The formula for calculating osmotic pressure is: In the formula, It is a constant (≈1.1). It is a simplified concentration. ≈0.588.

[0050] By adjusting the pore radius of the hydrophilic material, the modification time, or the polymer concentration, the thickness of the hydrophobic modification layer of the Janus membrane can be customized according to the above formula. For example, by shortening the modification time, a Janus structure with a thin hydrophobic layer and a thick hydrophilic layer can be obtained. This type of Janus structure can realize the directional transport of water droplets for fog collection or personal humidity management. By extending the modification time, a Janus structure that is half hydrophilic and half hydrophobic can be obtained, which can be used in membrane distillation to shorten the mass transfer distance and increase the mass transfer flux. By further extending the modification time or reducing the polymer concentration, a Janus structure with a thin hydrophilic layer and a thick hydrophobic layer can be obtained. This type of Janus structure can realize the directional transport of oil droplets and be used in oil-water emulsion separation.

[0051] We used a contact angle meter to test the wettability on both sides of the modified base film to clarify the asymmetric wettability of the prepared Janus film. In addition, we detected the thickness of the modified layer by fluorescence staining and observation using laser confocal microscopy. The controllability of the gel engineering was evaluated by observing the uniformity of the modified layer thickness in the cross section under a microscope. The adjustability of the gel engineering was reflected by the modified layer thickness measured under different conditions.

[0052] Examples 1-4 Polystyrene-polyisoprene-polystyrene (SIS) was selected as the block copolymer with a molecular weight of 100,000, and hexadecane was selected as the organic solvent.

[0053] In Examples 1-4, the mass concentrations of the block copolymers in the modified solutions were 7.5 wt%, 10 wt%, 12.5 wt%, and 15 wt%, respectively.

[0054] Octadecyltrichlorosilane was selected as the hydrophobic modifier. In Examples 1-4, the concentration of the hydrophobic modifier in the modification solution was 25 μL / g. The concentration of the hydrophobic modifier did not affect the wettability and thickness of the modified layer.

[0055] Choose a dissolution temperature of 120°C. o C, the unilateral hydrophobic modification temperature is selected as 25°C. o C.

[0056] Polyethersulfone was selected as the hydrophilic porous membrane material, with a nominal pore size of 0.22 μm and a porosity of 70%.

[0057] The oleogels prepared in Examples 1-4 maintain a balance between elastic potential energy and osmotic pressure due to the swelling of the block copolymer crosslinking network. The osmotic pressure of the oleogels at different block copolymer concentrations is shown in Table 1.

[0058] Table 1 The oleogels prepared in Examples 1-4 were used to modify hydrophilic porous membrane materials (pore size 0.22 μm) to form Janus structures through unilateral hydrophobic modification. The consistency of modification time (75 s), membrane pore size, and operating pressure was controlled. The effect of different block copolymer concentrations on the modified layer thickness is shown in Table 2.

[0059] Table 2 Examples 5-7 In Examples 5-7, Janus membranes were prepared by replacing hydrophilic porous membrane materials with different pore sizes under the same block copolymer mass concentration (10 wt%) as in Example 2.

[0060] In Examples 5-7, the block copolymer concentration was 10 wt%, and the pore sizes of the polyethersulfone hydrophilic porous membrane materials were 0.03 μm, 0.1 μm, and 0.45 μm, respectively.

[0061] One-sided hydrophobic modification of polyethersulfone porous hydrophilic membrane materials with different pore sizes was performed using an oleogel prepared with a polymer mass concentration of 10 wt%, while maintaining a consistent modification time (75 s). The thicknesses of the resulting modified layers are shown in Table 3.

[0062] Table 3 Examples 8-11 In Examples 8-11, Janus membranes were prepared under the same polymer mass concentration and membrane pore size conditions as in Example 2, but with the modification time replaced.

[0063] In Examples 8-11, the polymer concentration was 10 wt%, the pore size of the hydrophilic porous membrane material was 0.22 μm, and the modification times were 15 s, 30 s, 45 s, and 60 s, respectively.

[0064] One-sided hydrophobic modification of a 0.22 μm porous hydrophilic polyethersulfone membrane material was performed using an oleogel prepared with a polymer mass concentration of 10 wt%. The thickness of the modified layer obtained by selecting different modification times is shown in Table 4.

[0065] Table 4 Examples 12-15 Examples 8-11 were modified by replacing the hydrophobic modifier with 1H,1H,2H,2H-perfluorooctyltrichlorosilane for Examples 12-15.

[0066] In Examples 12-15, the polymer concentration was 10 wt%, the pore size of the hydrophilic porous membrane material was 0.22 μm, and the modification time was 15 s, 30 s, 45 s, and 60 s, respectively.

[0067] The thicknesses of the modified layers obtained by selecting different modification times are shown in Table 5.

[0068] Table 5 Examples 16-19 Examples 16-19 were carried out by replacing the polyethersulfone porous membrane material used in Examples 1-4 with a porous alumina ceramic membrane.

[0069] The polymer mass concentrations used in Examples 16-19 were 7.5 wt%, 10.0 wt%, 12.5 wt%, and 15.0 wt%, respectively.

[0070] The oleogels prepared in Examples 16-19 were used to construct Janus structures by unilateral hydrophobic modification of porous alumina ceramic materials (pore size 0.5 μm). The effects of different polymer concentrations on the thickness of the modified layer were obtained by controlling the consistency of modification time (30 s), membrane pore size, and operating pressure, as shown in Table 6.

[0071] Table 6 Examples 20-22 The pore size of the alumina porous ceramic material used in Example 18 was replaced in Examples 16-18.

[0072] The polymers used in Examples 20-22 had a mass concentration of 12.5 wt% and pore sizes of 0.05 μm, 0.1 μm, and 2.0 μm, respectively.

[0073] Examples 20-22 illustrate the unilateral hydrophobic modification of polyethersulfone porous hydrophilic membrane materials with different pore sizes using an oleogel prepared with a polymer mass concentration of 10 wt%. The modification time (30 s) was kept consistent. The thicknesses of the modified layers are shown in Table 7.

[0074] Table 7 Examples 23-26 Examples 23-26 were prepared under the same polymer concentration and membrane pore size conditions as in Example 18, but with a different modification time.

[0075] In Examples 23-26, the polymer concentration was 12.5 wt%, and the hydrophilic membrane pore size was 0.5 μm. The modification times were 45 s, 60 s, 90 s, and 120 s, respectively.

[0076] One-sided hydrophobic modification of a 0.22 μm porous hydrophilic polyethersulfone membrane material was performed using an oleogel prepared with a polymer mass concentration of 10 wt%. The thickness of the modified layer obtained by selecting different modification times is shown in Table 8.

[0077] Table 8 The Janus membranes prepared in the above embodiments have a hydrophilic contact angle of less than 40° and a hydrophobic contact angle of greater than 120°, exhibiting good asymmetric wettability.

[0078] like Figure 2 As shown, yellow represents the thickness of the hydrophobic modified layer. The thickness of the hydrophobic modified layer of the Janus membrane is controlled by adjusting the pore radius of the hydrophilic porous membrane material, the viscosity of the modified solvent, the hydrophobic modification time, and the concentration of the polymer in the sol.

[0079] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a gel-assisted bifacial membrane, characterized in that, Includes the following steps: (1) Dissolve the polymer in a modified solvent, and then add a hydrophobic modifier to obtain a uniformly mixed sol; (2) Spread the sol into a flat liquid film and cool it to room temperature to obtain a gel; (3) The surface of the hydrophilic porous membrane material is brought into contact with the surface of the gel so that the hydrophobic modifier of the gel modifies the surface of the hydrophilic porous membrane material. After separation, a bifacial membrane material with unilateral hydrophobic modification is obtained.

2. The method for preparing a gel-assisted dihedral membrane according to claim 1, characterized in that, The thickness of the hydrophobic modified layer of the zeta membrane material can be controlled by adjusting the pore radius of the hydrophilic porous membrane material, the viscosity of the modified solvent, the hydrophobic modification time, and the concentration of the polymer in the sol.

3. The method for preparing a gel-assisted dihedral membrane according to claim 1 or 2, characterized in that, Thickness of the hydrophobic modified layer of the two-sided membrane material Calculated by the following formula: In the formula, The pore radius of the hydrophilic porous membrane material; The viscosity of the modified solvent; For capillary force; Osmotic pressure, For modification time; Among them, capillary force The calculation formula is: In the formula, The surface tension coefficient of the modified solvent; The contact angle of the modified solvent on the surface of the hydrophilic porous membrane material; osmotic pressure The calculation formula is: In the formula, ≈1.1, It is a simplified concentration. ≈0.

588.

4. The method for preparing a gel-assisted malignant membrane according to claim 1, characterized in that, The polymer is a block copolymer; the block copolymer is at least one of polystyrene-polyisoprene-polystyrene, polystyrene-polybutadiene-polystyrene, polystyrene-polyethylene glycol-polystyrene, and polystyrene-polysiloxane-polystyrene.

5. The method for preparing a gel-assisted malignant membrane according to claim 1, characterized in that, The hydrophobic modifier is at least one of chlorosilane, fluorochlorosilane, and fluorosiloxane.

6. The method for preparing a gel-assisted malignant membrane according to claim 5, characterized in that, The hydrophobic modifier is at least one of octadecyltrichlorosilane, hexadecyltrichlorosilane, tetradecyltrichlorosilane, dodecyltrichlorosilane, 1H,1H,2H,2H-perfluorooctyltrichlorosilane, 1H,1H,2H,2H-perfluorodecyltrichlorosilane, 1H,1H,2H,2H-perfluorohexyltrichlorosilane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, 1H,1H,2H,2H-perfluorohexyltriethoxysilane, 1H,1H,2H,2H-perfluorohexyltrimethoxysilane, 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, and 1H,1H,2H,2H-perfluorodecyltrimethoxysilane.

7. The method for preparing a gel-assisted dihedral membrane according to claim 1, characterized in that, In the sol, the polymer concentration is 5-25 wt% and the hydrophobic modifier concentration is 0.5-50 μL / g.

8. The method for preparing a gel-assisted malignant membrane according to claim 1, characterized in that, The hydrophilic porous membrane material has a pore size of 20 nm to 100 μm, a thickness of 50 to 500 μm, and a porosity of 50 to 80%.

9. A bifacial membrane material prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the bifacial membrane material of claim 9 in directional transport, oil-water separation or membrane distillation.

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