A Janus hydrophilic composite membrane and its preparation method and application

Abstract

The present invention discloses a Janus affinity-repellent composite membrane and a preparation method and application thereof. The Janus affinity-repellent composite membrane is a double-layer structure membrane prepared in one step by airflow-assisted jet electrostatic spinning technology. The bottom layer is a porous membrane formed by uniformly compounding the thermal conductivity factor collected by a pin-plate-shaped receiving device and hydrophobic thermal conductive micro-nano fibers, and the top layer is a porous membrane composed of mid-infrared emitting hydrophilic micro-nano fibers. The Janus affinity-repellent composite membrane is applied to the field of high-humidity cooling textiles to achieve heat management of people or objects. Due to the hydrophobicity, hydrophilicity, thermal conductivity, mid-infrared emissivity of the material itself, the directional water transport channel formed by the pore-pore gradient and the micro-nano size structure of the fibers in the top layer membrane, the Janus affinity-repellent composite membrane can integrate high thermal conductivity, daytime radiation cooling and evaporative cooling, thereby significantly improving the cooling performance of the material. The preparation process is simple, the industrial feasibility is large, and a new approach is provided for the development of cooling textiles.

Description

Technical Field

[0001] The present invention belongs to the field of functional textiles, and relates to a Janus affinity-repellent composite membrane for heat management, and a preparation method and application thereof, and specifically to a double-layer structure composite membrane integrating high thermal conductivity, daytime radiation refrigeration and evaporative cooling prepared by airflow-assisted counter-spray electrospinning technology, which is applied to the field of high-humidity cooling textiles. Background Art

[0002] As the global climate warms, extreme weather occurs frequently. When people are exposed to heat waves under direct sunlight, the risk of heat stroke (or heat stroke) increases significantly because sweat and heat cannot be discharged in time. In addition, the healthy growth of crops in the greenhouse also requires a constant temperature and humidity environment. At present, cooling textiles for heat management are mainly made by adding some cool factors or introducing phase change materials to make textiles have the cooling effect of rapid heat transfer and accelerated sweating; or by treating the surface of the fiber membrane with hydrophilicity and hydrophobicity and specially designing the fiber cross-sectional structure to increase the moisture absorption and sweating capacity of the fiber membrane, and using evaporative heat absorption to enhance the cooling effect of the textile. The disadvantage is that the preparation process of these methods is relatively cumbersome, and the cooling effect needs to be further improved. Therefore, it is necessary to invent an efficient cooling textile that synergistically promotes the effects of thermal radiation, heat conduction and evaporative cooling to maximize heat dissipation and obtain thermal comfort for people or objects. Summary of the invention

[0003] In view of the limitations of the prior art, the present invention proposes a Janus affinity-repellent composite membrane and its preparation method and application, that is, a double-layer composite membrane is prepared by airflow-assisted counter-spray electrospinning technology, the bottom layer of which is a porous membrane uniformly compounded by thermal conductivity factors and hydrophobic thermal conductive micro-nano fibers collected by a specially designed needle-plate-shaped receiving device, and the top layer is a porous membrane composed of mid-infrared emitting hydrophilic micro-nano fibers, which is applied to the field of high-humidity cooling textiles to achieve heat management of people or objects. This specially designed Janus affinity-repellent composite membrane is able to integrate high thermal conductivity, daytime radiation cooling and evaporative cooling due to the hydrophobicity, hydrophilicity, thermal conductivity, mid-infrared emissivity of the material itself, the directional water transfer channel formed by the pore-pore gradient, and the micro-nano size structure of the fibers in the top layer membrane, thereby significantly improving the cooling performance. The specific technical scheme is as follows:

[0004] A Janus hydrophilic composite membrane is a double-layer composite membrane composed of a top porous membrane and a bottom porous membrane, with a thickness greater than or equal to 10 μm. The top layer is a porous membrane composed of mid-infrared emitting hydrophilic micro-nano fibers, with a fiber diameter of 10-2500 nm and a pore size of 50-50000 nm between fibers. The bottom layer is a porous membrane collected by a specially designed pin-plate-shaped receiving device and uniformly compounded with thermal conductivity factors and hydrophobic thermal conductive micro-nano fibers, with a fiber diameter of 10-2500 nm, thermal conductivity factors can be in the form of particles, lines or sheets, the distance between holes is 1-10 mm, and the hole diameter is 1-5 mm.

[0005] The hole and pore sizes should be coordinated from large to small in a gradient to form a directional water transfer channel.

[0006] The Janus hydrophilic composite membrane is prepared in one step by an airflow-assisted jet electrostatic spinning device.

[0007] Furthermore, the airflow-assisted counter-jet electrospinning device consists of a liquid supply device, a spinning unit, a high-voltage generating device, a receiving device, an air supply device, an airflow nozzle, etc.; the air supply device is connected to the air inlet of the airflow nozzle; the liquid supply device is connected to the spinning unit; there are two spinning units and they are placed horizontally opposite to each other, with a distance of 1-50 cm between the two spinning units; the positive and negative electrodes of the high-voltage generating device are respectively connected to the left and right spinning units; the receiving device is located directly below the center of the two spinning units; the airflow nozzle is directly above the center of the two spinning units; the receiving device is 5-100 cm away from the airflow nozzle.

[0008] Furthermore, the air flow nozzle consists of an air inlet and an air outlet, the air inlet is a cylindrical structure with an inner diameter of 4-10 mm, an outer diameter of 8-15 mm, and a height of 10-20 mm, the air outlet is a rectangular structure with a length of 20-40 mm and a width of 1.5-3 mm, and the outer shell of the air flow nozzle is a rectangular structure with a length of 50-60 mm, a width of 30-40 mm, and a height of 60-80 mm.

[0009] Furthermore, the spinning unit is a common needle structure, and the inner diameter of the needle is 0.1-5 mm.

[0010] Furthermore, the receiving device is composed of a base, a needle bar, a lifting device, a connecting rod and a receiving plate. The base is a rectangular parallelepiped structure with a length of 100-200mm, a width of 100-200mm and a height of 10-30mm. Needles with a diameter of 1-5mm, a height of 5-20mm and a spacing of 1-10mm are evenly distributed on the base; the lifting device is fixed on the base to control the up and down movement of the receiving plate; the two ends of the connecting rod are respectively connected to the lifting device and the receiving plate; the receiving plate is a rectangular parallelepiped structure with a length of 50-150mm, a width of 50-150mm and a height of 5-15mm, and the receiving plate is provided with holes that match the needle bars on the base. During spinning, due to the presence of the needle bars, the fibers can only be deposited between the needle bars on the receiving plate. When the receiving plate moves upward to remove the needle bars, regularly arranged holes will be formed on the fiber membrane.

[0011] The preparation method of the Janus hydrophilic composite membrane of the present invention specifically comprises the following steps:

[0012] (1) adding the thermal conductivity factor into an ethanol solution, and obtaining a thermal conductivity factor dispersion having a concentration of 0.01-10 g / ml after ultrasonic dispersion;

[0013] (2) Stirring the hydrophobic thermal conductive polymer and the solvent by a magnetic stirrer at 20-95° C. for 1-24 h until the mixture is uniformly mixed, wherein the mass concentration of the thermal conductive polymer is 5-50%;

[0014] (3) Stirring the hydrophilic polymer and the solvent by a magnetic stirrer at 20-95° C. for 1-24 hours until the mixture is uniformly mixed, wherein the mass concentration of the hydrophilic polymer is 5-50%;

[0015] (4) placing the thermal conductivity factor dispersion prepared in step (1) and the polymer spinning solution prepared in step (2) in two spinning units on the left and right respectively, and performing airflow-assisted jet electrospinning; the product prepared by the spinning unit on the right side containing the thermal conductivity factor dispersion is the thermal conductivity factor (particles or sheets), while the product prepared by the spinning unit on the left side containing the polymer spinning solution is the hydrophobic thermal conductive micro-nano fiber. Under the action of the airflow, the thermal conductivity factor (particles or sheets) and the hydrophobic thermal conductive micro-nano fiber are simultaneously deposited on the surface of the receiving plate. Due to the presence of the needle rod, the fiber membrane finally formed is a membrane with a regularly arranged pore structure formed by a mixture of the thermal conductivity factor and the hydrophobic thermal conductive micro-nano fiber;

[0016] (5) When the porous film prepared in step (4) is deposited to a certain thickness, the receiving plate is moved upward to a position where the upper surface of the receiving plate is equal to or higher than the top surface of the needle rod;

[0017] (6) The polymer spinning solution in step (3) is placed in two spinning units to continuously prepare mid-infrared emitting hydrophilic micro-nano fibers. The mid-infrared emitting hydrophilic micro-nano fibers are directly deposited on the surface of the porous membrane, and finally a double-layer Janus hydrophobic composite membrane is obtained.

[0018] Furthermore, the thermal conductivity factor in step (1) should have high thermal conductivity, with a thermal conductivity coefficient of more than 3000 W / mk, such as graphene sheets, carbon nanotubes, nanosilver particles, etc.

[0019] Furthermore, the hydrophobic high molecular polymer in step (2) can be prepared by an electrospinning method, such as polyurethane, polyvinylidene fluoride, polylactic acid, polyurethane, etc.; the solvent is deionized water, dichloromethane, tetrahydrofuran THF, N,N-dimethylformamide DMF, N,N-dimethylacetamide DMAC, acetone, or a mixed solvent of THF and DMF, or a mixed solvent of DMAC and acetone.

[0020] Furthermore, the hydrophilic high molecular polymer in step (3) can be prepared by an electrospinning method and has an emission function in the mid-infrared spectral band (2.5-25 μm), such as cellulose acetate, fluorinated polyethylene, polyvinyl alcohol, etc.

[0021] The Janus affinity-repellency composite film of the present invention can be applied to the field of high-humidity cooling textiles to manage the heat of people or objects.

[0022] Beneficial effects of the present invention: First, the Janus affinity-repellent composite membrane of the present invention is prepared in one step by an independently designed airflow-assisted jet electrostatic spinning technology. The process is simple and reliable, and the industrial feasibility is large, providing a new method for the development of cooling textiles. Second, the Janus affinity-repellent composite membrane prepared by the present invention has a bottom layer of a porous membrane collected by a specially designed pin-plate-shaped receiving device and uniformly compounded by thermal conductivity factors and hydrophobic thermal conductive micro-nano fibers, and a top layer of a porous membrane composed of mid-infrared emitting hydrophilic micro-nano fibers. This Janus affinity-repellent composite membrane is due to the hydrophobicity, hydrophilicity, thermal conductivity, mid-infrared emissivity of the material itself, as well as the directional water transport channel coordinated by the pore-pore gradient and the micro-nano size structure of the fibers in the top layer membrane, so that the Janus affinity-repellent composite membrane can integrate high thermal conductivity, daytime radiation cooling and evaporative cooling, thereby significantly improving the cooling performance, and the cooling can reach up to 13°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of the airflow-assisted jet electrospinning device.

[0024] Figure 2 Schematic diagram of the Janus hydrophilic composite membrane structure.

[0025] Figure 3Schematic diagram of the air flow nozzle structure.

[0026] Figure 4 A schematic diagram of the structure of a receiving device. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention, and those skilled in the art in this field can make some non-essential improvements and adjustments based on the content of the above invention.

[0028] Example 1

[0029] The Janus hydrophilic composite membrane used in this embodiment is used in the field of high-humidity cooling textiles. Figure 1 The airflow-assisted electrostatic spinning device shown is prepared, comprising a liquid supply device 1, a spinning unit 2, a high-voltage generating device 3, a receiving device 4, an air supply device 5, an air nozzle 6, etc.; the liquid supply device 1 is connected to the spinning unit 2; there are two spinning units 2 and they are placed horizontally opposite to each other, and the two spinning units 2 are 30 cm apart; the positive electrode and the negative electrode of the high-voltage generating device 3 are respectively connected to the left and right spinning units; the airflow nozzle is directly above the center of the two spinning units; the air supply device 5 is connected to the air inlet of the air nozzle 6, the air inlet is a cylindrical structure with an inner diameter of 6 mm, an outer diameter of 8 mm, and a height of 10 mm, the air outlet is a rectangular structure with a length of 40 mm and a width of 2 mm, and the outer shell of the airflow nozzle is a rectangular structure with a length of 50 mm, a width of 30 mm, and a height of 60 mm; the receiving device 4 is located directly below the center of the two spinning units 2; the receiving device is 36 cm away from the airflow nozzle; The receiving device consists of a base 4-1, a needle bar 4-2, a lifting device 4-3, a connecting rod 4-4 and a receiving plate 4-5. The base is a rectangular structure with a length of 150 mm, a width of 150 mm and a height of 15 mm, and needle bars with a diameter of 2 mm, a height of 15 mm and a spacing of 3 mm are evenly distributed on the base; the lifting device is fixed on the base to control the up and down movement of the receiving plate; the two ends of the connecting rod are respectively connected to the lifting device and the receiving plate; the receiving plate is a rectangular structure with a length of 100 mm, a width of 100 mm and a height of 5 mm, and the receiving plate is provided with holes that match the needle bars on the base.

[0030] The steps of using the above-mentioned airflow-assisted jet electrospinning device to prepare a Janus hydrophilic composite membrane for use in the field of high-humidity cooling textiles are as follows:

[0031] (1) adding graphene sheets into an ethanol solution and obtaining a graphene oxide sheet dispersion with a concentration of 10 g / ml after ultrasonic dispersion;

[0032] (2) At 80° C., a polyvinylidene fluoride polymer and a mixed solvent (DMF and THF in a mass ratio of 1:1) were stirred by a magnetic stirrer for 8 h until the mixture was uniformly mixed, thereby obtaining a polyvinylidene fluoride spinning solution with a mass concentration of 15%;

[0033] (3) using a magnetic stirrer to stir the cellulose acetate polymer and the mixed solvent (DMAC and acetone in a mass ratio of 1:2) for 3 h until the mixture is uniform, thereby obtaining a cellulose acetate spinning solution with a mass concentration of 13%;

[0034] (4) The graphene oxide sheet dispersion and polyvinylidene fluoride spinning solution obtained in step (1) are placed in two spinning units on the left and right respectively, and airflow-assisted counter-jet electrospinning is performed; the product prepared by the spinning unit on the right side containing the graphene oxide sheet dispersion is graphene oxide sheet, and the inner diameter of the needle of the spinning unit is 1 mm; while the product prepared by the spinning unit on the left side containing the polyvinylidene fluoride spinning solution is polyvinylidene fluoride micro-nano fiber, and the inner diameter of the needle of the spinning unit is 1 mm; under the action of the airflow, the graphene oxide sheet and the polyvinylidene fluoride micro-nano fiber are simultaneously deposited on the surface of the receiving plate. Due to the presence of the needle bar, the fiber membrane finally formed is a membrane with a regularly arranged pore structure formed by a mixture of graphene oxide sheet and polyvinylidene fluoride micro-nano fiber, and the pore diameter is 2 mm;

[0035] (5) When the thickness of the hole film prepared in step (4) is deposited to 100 μm, the receiving plate is moved upward until it is completely separated from the needle bar;

[0036] (6) The cellulose acetate spinning solution in step (3) is placed in two spinning units to continuously prepare cellulose acetate fibers. The cellulose acetate fibers are directly deposited on the surface of the porous membrane. The deposited double-layer membrane is immersed in a NaOH solution with a concentration of 0.5 mol / L for 0.5 h to finally obtain a double-layer Janus hydrophilic composite membrane with a thickness of 300 μm.

[0037] The graphene / polyvinylidene fluoride-cellulose acetate Janus affinity-repellency composite membrane prepared in this embodiment shows excellent cooling performance, and the cooling can reach 13°C.

[0038] Example 2

[0039] The Janus hydrophilic composite membrane used in this embodiment is used in the field of high-humidity cooling textiles. Figure 1The airflow-assisted electrostatic spinning device shown in the figure is prepared, including a liquid supply device 1, a spinning unit 2, a high-voltage generating device 3, a receiving device 4, an air supply device 5, an air nozzle 6, etc.; the liquid supply device 1 is connected to the spinning unit 2; the spinning unit 2 has two and is placed horizontally opposite to each other, and the two spinning units 2 are 35 cm apart; the positive electrode and the negative electrode of the high-voltage generating device 2 are respectively connected to the left and right spinning units; the airflow nozzle is directly above the center of the two spinning units; the air supply device 5 is connected to the air inlet of the air nozzle 6, the air inlet is a cylindrical structure with an inner diameter of 6 mm, an outer diameter of 8 mm, and a height of 10 mm, the air outlet is a rectangular structure with a length of 40 mm and a width of 2 mm, and the outer shell of the airflow nozzle is a rectangular structure with a length of 50 mm, a width of 30 mm, and a height of 60 mm; the receiving device 4 is located directly below the center of the two spinning units 2; the receiving device and the airflow nozzle The spacing is 36cm; the receiving device consists of a base, a needle bar, a lifting device, a connecting rod and a receiving plate. The base is a rectangular structure with a length of 150mm, a width of 150mm and a height of 15mm, and needle bars with a diameter of 2mm, a height of 15mm and a spacing of 3mm are evenly distributed on the base; the lifting device is fixed on the base to control the up and down movement of the receiving plate; the two ends of the connecting rod are respectively connected to the lifting device and the receiving plate; the receiving plate is a rectangular structure with a length of 100mm, a width of 100mm and a height of 5mm, and the receiving plate is provided with holes that match the needle bars on the base.

[0040] The steps of using the above-mentioned airflow-assisted jet electrospinning device to prepare a Janus hydrophilic composite membrane for use in the field of high-humidity cooling textiles are as follows:

[0041] (4) adding carbon nanotubes into an ethanol solution and obtaining a carbon nanotube dispersion with a concentration of 5 g / ml after ultrasonic dispersion;

[0042] (5) At 80° C., the polyvinylidene fluoride polymer and the mixed solvent (DMF and THF in a mass ratio of 1:1) were stirred by a magnetic stirrer for 8 h until the mixture was uniformly mixed, thereby obtaining a polyvinylidene fluoride spinning solution with a mass concentration of 15%;

[0043] (6) using a magnetic stirrer to stir the cellulose acetate polymer and the mixed solvent (DMAC and acetone in a mass ratio of 1:2) for 3 h until the mixture is uniform, thereby obtaining a cellulose acetate spinning solution with a mass concentration of 13%;

[0044] (4) The carbon nanotube dispersion and polyvinylidene fluoride spinning solution obtained in step (1) are placed in two spinning units on the left and right respectively, and airflow-assisted counter-spray electrospinning is performed; the product prepared by the spinning unit on the right side containing the carbon nanotube dispersion is carbon nanotubes, and the inner diameter of the needle of the spinning unit is 1 mm; while the product prepared by the spinning unit on the left side containing the polyvinylidene fluoride spinning solution is polyvinylidene fluoride micro-nanofibers, and the inner diameter of the needle of the spinning unit is 1 mm; under the action of the airflow, the carbon nanotubes and the polyvinylidene fluoride micro-nanofibers are simultaneously deposited on the surface of the receiving plate. Due to the presence of the needle rod, the fiber membrane finally formed is a membrane with a regularly arranged pore structure formed by a mixture of carbon nanotubes and polyvinylidene fluoride micro-nanofibers, and the pore diameter is 2 mm;

[0045] (5) When the thickness of the hole film prepared in step (4) is deposited to 100 μm, the receiving plate is moved upward to a position where the upper surface of the receiving plate is flush with the top surface of the needle rod;

[0046] (6) The cellulose acetate spinning solution in step (3) is placed in two spinning units to continuously prepare cellulose acetate fibers. The cellulose acetate fibers are directly deposited on the surface of the porous membrane. The deposited double-layer membrane is immersed in a NaOH solution with a concentration of 0.5 mol / L for 0.5 h to finally obtain a double-layer Janus hydrophilic composite membrane with a thickness of 300 μm.

[0047] Example 3

[0048] The Janus hydrophilic composite membrane used in this embodiment is used in the field of high-humidity cooling textiles. Figure 1The airflow-assisted electrostatic spinning device shown is prepared, comprising a liquid supply device 1, a spinning unit 2, a high-voltage generating device 3, a receiving device 4, an air supply device 5, an air nozzle 6, etc.; the liquid supply device 1 is connected to the spinning unit 2; there are two spinning units 2 and they are placed horizontally opposite to each other, and the two spinning units 2 are 20 cm apart; the positive electrode and the negative electrode of the high-voltage generating device 2 are respectively connected to the left and right spinning units; the airflow nozzle is directly above the center of the two spinning units; the air supply device 5 is connected to the air inlet of the air nozzle 6, the air inlet is a cylindrical structure with an inner diameter of 8 mm, an outer diameter of 10 mm, and a height of 15 mm, the air outlet is a rectangular structure with a length of 45 mm and a width of 3 mm, and the outer shell of the airflow nozzle is a rectangular structure with a length of 55 mm, a width of 35 mm, and a height of 60 mm; the receiving device 4 is located directly below the center of the two spinning units 2. The receiving device is 40 cm away from the airflow nozzle; the receiving device consists of a base, a needle rod, a lifting device, a connecting rod and a receiving plate. The base is a rectangular structure with a length of 200 mm, a width of 200 mm and a height of 20 mm, and needle rods with a diameter of 3 mm, a height of 20 mm and a spacing of 5 mm are evenly distributed on the base; the lifting device is fixed on the base to control the up and down movement of the receiving plate; the two ends of the connecting rod are respectively connected to the lifting device and the receiving plate; the receiving plate is a rectangular structure with a length of 150 mm, a width of 150 mm and a height of 10 mm, and the receiving plate is provided with holes that match the needle rods on the base.

[0049] The steps of using the above-mentioned airflow-assisted jet electrospinning device to prepare a Janus hydrophilic composite membrane for use in the field of high-humidity cooling textiles are as follows:

[0050] (1) adding silver microsheets into an ethanol solution and obtaining a silver microsheet dispersion with a concentration of 5 g / ml after ultrasonic dispersion;

[0051] (2) Stirring the polyurethane polymer and the mixed solvent (DMF and THF in a mass ratio of 1:1) at 80°C for 8 h by a magnetic stirrer until the mixture is uniformly mixed, thereby obtaining a polyurethane spinning solution with a mass concentration of 15%;

[0052] (3) using a magnetic stirrer to stir the cellulose acetate polymer and the mixed solvent (DMAC and acetone in a mass ratio of 1:2) for 3 h until the mixture is uniform, thereby obtaining a cellulose acetate spinning solution with a mass concentration of 13%;

[0053] (4) The silver microsheet dispersion and the polyurethane spinning solution obtained in step (1) are placed in two spinning units on the left and right, respectively, to perform airflow-assisted electrospinning. The product prepared by the spinning unit on the right with the silver microsheet dispersion is silver microsheets, and the inner diameter of the needle of the spinning unit is 1 mm. The product prepared by the spinning unit on the left with the polyurethane spinning solution is polyurethane micro-nanofibers, and the inner diameter of the needle of the spinning unit is 1 mm. Under the action of the airflow, the silver microsheets and the polyurethane micro-nanofibers are simultaneously deposited on the surface of the receiving plate. Due to the presence of the needle bar, the fiber membrane finally formed is a membrane with a regularly arranged pore structure formed by a mixture of silver microsheets and polyurethane micro-nanofibers, and the pore diameter is 3 mm.

[0054] (5) When the thickness of the hole film prepared in step (4) is deposited to 100 μm, the receiving plate is moved upward until it is completely separated from the needle bar;

[0055] (6) The cellulose acetate spinning solution in step (3) is placed in two spinning units to continuously prepare cellulose acetate fibers. The cellulose acetate fibers are directly deposited on the surface of the porous membrane. The deposited double-layer membrane is immersed in a NaOH solution with a concentration of 0.5 mol / L for 0.5 h to finally obtain a double-layer Janus hydrophilic composite membrane with a thickness of 300 μm.

[0056] Example 4

[0057] The Janus hydrophilic composite membrane used in this embodiment is used in the field of high-humidity cooling textiles. Figure 1The airflow-assisted electrostatic spinning device shown in the figure is prepared, comprising a liquid supply device 1, a spinning unit 2, a high-voltage generating device 3, a receiving device 4, an air supply device 5, an air nozzle 6, etc.; the liquid supply device 1 is connected to the spinning unit 2; the spinning unit 2 has two and is placed horizontally opposite to each other, and the two spinning units 2 are 20 cm apart; the positive electrode and the negative electrode of the high-voltage generating device 2 are respectively connected to the left and right spinning units; the airflow nozzle is directly above the center of the two spinning units; the air supply device 5 is connected to the air inlet of the air nozzle 6, the air inlet is a cylindrical structure with an inner diameter of 8 mm, an outer diameter of 10 mm, and a height of 15 mm, the air outlet is a rectangular structure with a length of 45 mm and a width of 3 mm, and the outer shell of the airflow nozzle is a rectangular structure with a length of 55 mm, a width of 35 mm, and a height of 60 mm; the receiving device 4 is located directly below the center of the two spinning units 2; the receiving device and the airflow nozzle The spacing is 40cm; the receiving device consists of a base, a needle bar, a lifting device, a connecting rod and a receiving plate. The base is a rectangular structure with a length of 200mm, a width of 200mm and a height of 20mm, and needle bars with a diameter of 3mm, a height of 20mm and a spacing of 5mm are evenly distributed on the base; the lifting device is fixed on the base to control the up and down movement of the receiving plate; the two ends of the connecting rod are respectively connected to the lifting device and the receiving plate; the receiving plate is a rectangular structure with a length of 150mm, a width of 150mm and a height of 10mm, and the receiving plate is provided with holes that match the needle bars on the base.

[0058] The steps of using the above-mentioned airflow-assisted jet electrospinning device to prepare a Janus hydrophilic composite membrane for use in the field of high-humidity cooling textiles are as follows:

[0059] (1) Adding boron nitride nanosheets into an ethanol solution, and obtaining a boron nitride nanosheet dispersion with a concentration of 5 g / ml after ultrasonic dispersion;

[0060] (2) Stirring the polyurethane polymer and the mixed solvent (DMF and THF in a mass ratio of 1:1) at 80°C for 8 h by a magnetic stirrer until the mixture is uniformly mixed, thereby obtaining a polyurethane spinning solution with a mass concentration of 15%;

[0061] (3) using a magnetic stirrer to stir the cellulose acetate polymer and the mixed solvent (DMAC and acetone in a mass ratio of 1:2) for 3 h until the mixture is uniform, thereby obtaining a cellulose acetate spinning solution with a mass concentration of 13%;

[0062] (4) The boron nitride nanosheet dispersion and the polyurethane spinning solution obtained in step (1) are placed in two spinning units on the left and right respectively, and airflow-assisted counter-jet electrospinning is performed; the product prepared by the spinning unit on the right side containing the boron nitride nanosheet dispersion is boron nitride nanosheets, and the inner diameter of the needle of the spinning unit is 1 mm; while the product prepared by the spinning unit on the left side containing the polyurethane spinning solution is polyurethane micro-nanofibers, and the inner diameter of the needle of the spinning unit is 1 mm; under the action of the airflow, the boron nitride nanosheets and the polyurethane micro-nanofibers are simultaneously deposited on the surface of the receiving plate. Due to the presence of the needle bar, the fiber membrane finally formed is a membrane with a regularly arranged pore structure formed by a mixture of boron nitride nanosheets and polyurethane micro-nanofibers, and the pore diameter is 1 mm;

[0063] (5) When the thickness of the porous membrane prepared in step (4) is deposited to 50 μm, the receiving plate is moved upward to a position half the thickness of the porous membrane (i.e., 25 μm from the upper surface of the porous membrane);

[0064] (6) The cellulose acetate spinning solution in step (3) is placed in two spinning units to continuously prepare cellulose acetate fibers. The cellulose acetate fibers are directly deposited on the surface of the porous membrane. The deposited double-layer membrane is immersed in a NaOH solution with a concentration of 0.5 mol / L for 0.5 h to finally obtain a double-layer Janus hydrophilic composite membrane with a thickness of 200 μm.

[0065] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A Janus affinity-repellent composite membrane, characterized in that: The Janus hydrophilic composite membrane is a double-layer structure membrane composed of a top porous membrane and a bottom porous membrane, with a thickness of ≥10 μm; the top porous membrane is a porous membrane composed of mid-infrared emitting hydrophilic micro-nano fibers, with a fiber diameter of 10-2500 nm, and a pore size between the hydrophilic micro-nano fibers of 50-50000 nm; the bottom porous membrane is a porous membrane collected by a pin-plate-shaped receiving device and uniformly composited with a thermal conductivity factor and hydrophobic thermal conductive micro-nano fibers, the diameter of the hydrophobic thermal conductive fiber is 10-2500 nm, the thermal conductivity factor is a particle, a wire or a sheet, the distance between the holes is 1-10 mm, and the hole diameter is 1-5 mm; The receiving device (4) is composed of a base (4-1), a needle bar (4-2), a lifting device (4-3), a connecting rod (4-4) and a receiving plate (4-5). The base (4-1) is a rectangular parallelepiped structure with a length of 100-200 mm, a width of 100-200 mm and a height of 10-30 mm. The base (4-1) is evenly distributed with cylindrical needle bars (4-2) with a diameter of 1-5 mm, a height of 5-20 mm and a spacing of 1-10 mm. The lifting device (4-3) is fixed on the base to control the up and down movement of the receiving plate (4-5); the two ends of the connecting rod (4-4) are respectively connected to the lifting device (4-3) and the receiving plate (4-5); the receiving plate (4-5) is a rectangular parallelepiped structure with a length of 50-150 mm, a width of 50-150 mm, and a height of 5-15 mm, and the receiving plate (4-5) is provided with a hole that matches the cylindrical needle rod (4-2) on the base (4-1).

2. The Janus affinity-repellent composite membrane according to claim 1, characterized in that: The Janus hydrophilic composite membrane is prepared in one step by an airflow-assisted jet electrostatic spinning device, which comprises a liquid supply device (1), a spinning unit (2), a high-voltage generating device (3), a receiving device (4), an air supply device (5), and an airflow nozzle (6); the air supply device (5) is connected to an air inlet of the airflow nozzle (6), the liquid supply device (1) is connected to the spinning unit (2), the spinning units (2) have two and are arranged horizontally opposite to each other, and the distance between the two spinning units is 1-50 cm; the positive electrode and the negative electrode of the high-voltage generating device (3) are respectively connected to the two spinning units (2) arranged horizontally opposite to each other; the receiving device (4) is located directly below the center of the two spinning units; the airflow nozzle is located directly above the center of the two spinning units; the distance between the receiving device (4) and the airflow nozzle (6) is 5-100 cm.

3. The Janus affinity-repellent composite membrane according to claim 2, characterized in that: The air flow nozzle (6) is composed of an air inlet and an air outlet. The air inlet is a cylindrical structure with an inner diameter of 4-10 mm, an outer diameter of 8-15 mm, and a height of 10-20 mm. The air outlet is a rectangular structure with a length of 20-40 mm and a width of 1.5-3 mm. The outer shell of the air flow nozzle is a rectangular structure with a length of 50-60 mm, a width of 30-40 mm, and a height of 60-80 mm. The spinning unit is a common needle structure with an inner diameter of 0.1-5 mm.

4. The method for preparing the Janus affinity-repellent composite membrane according to claim 2, characterized in that The following steps are involved: (1) adding the thermal conductivity factor into an ethanol solution, and obtaining a thermal conductivity factor dispersion having a concentration of 0.01-10 g / ml after ultrasonic dispersion; (2) stirring the hydrophobic thermal conductive polymer and the solvent by a magnetic stirrer at 20-95° C. for 1-24 hours until the mixture is uniformly mixed to obtain a hydrophobic thermal conductive polymer spinning solution, wherein the mass concentration of the hydrophobic thermal conductive polymer is 5-50%; (3) stirring the hydrophilic polymer and the solvent by a magnetic stirrer at 20-95° C. for 1-24 h until the mixture is uniformly mixed to obtain a hydrophilic polymer spinning solution, wherein the mass concentration of the hydrophilic polymer is 5-50%; (4) placing the thermal conductivity factor dispersion obtained in step (1) and the polymer spinning solution obtained in step (2) in two spinning units respectively, and performing airflow-assisted jet electrospinning; under the action of the airflow, the thermal conductivity factor and the hydrophobic thermal conductive micro-nano fibers are simultaneously deposited on the surface of the receiving plate, and due to the presence of the needle rod, the fiber membrane finally formed is a porous membrane with a regular arrangement of holes formed by a mixture of the thermal conductivity factor and the hydrophobic thermal conductive micro-nano fibers; (5) When the porous film prepared in step (4) is deposited to a certain thickness, the receiving plate is moved upward to a position where the upper surface of the receiving plate is equal to or higher than the top surface of the needle rod; (6) The hydrophilic polymer spinning solution in step (3) is placed in two spinning units to continuously prepare mid-infrared emitting hydrophilic micro-nano fibers. The mid-infrared emitting hydrophilic micro-nano fibers are directly deposited on the surface of the porous membrane, and finally a double-layer Janus hydrophobic composite membrane is obtained.

5. The method for preparing the Janus affinity-repellent composite membrane according to claim 4, characterized in that: The thermal conductivity factor in step (1) has high thermal conductivity, and the thermal conductivity coefficient can reach more than 3000W / mk, and includes graphene, carbon nanotubes or nano silver particles.

6. The method for preparing the Janus affinity-repellent composite membrane according to claim 4, characterized in that: The hydrophobic thermal conductive polymer in step (2) includes polyurethane, polyvinylidene fluoride, polylactic acid, and polyurethane; the solvent is deionized water, dichloromethane, tetrahydrofuran (THF), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), acetone, or a mixed solvent of THF and DMF, or a mixed solvent of DMAC and acetone; the hydrophilic polymer in step (3) has an emission function in the mid-infrared spectrum band and a high solar reflectivity in the visible spectrum band, and includes cellulose acetate, fluorinated polyethylene, or polyvinyl alcohol.

7. The use of the Janus affinity-repellent composite membrane according to claim 1, characterized in that: The Janus hydrophilic composite film is applied to the field of high-humidity cooling textiles to achieve heat management of people and objects.

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