Method and apparatus for universal preparation of oriented nanofiber membranes

Abstract

The application provides a method and device for preparing oriented nanofiber membranes, which comprises the following steps: freezing polymer nanofibers with liquid nitrogen; sticking a substrate for preparing nanofiber membranes on the inner wall of a closed container of a device for preparing oriented nanofiber membranes; placing the frozen polymer nanofibers in the closed container and rotating at high speed; and finally taking off the substrate on the inner wall of the closed container, and the surface of the substrate is uniformly compounded with oriented polymer nanofibers, thus obtaining the oriented nanofiber membranes. The device for preparing oriented nanofiber membranes has a rotating component rotating at high speed, and under the action of high-speed shearing force, the device can realize the directional selection of nanofibers and apply centrifugal force to the fibers, so that the fibers are oriented and compounded with the substrate. The application can be applied to different polymer nanofiber materials, realizes the separation of fiber spinning and orientation process, overcomes the dependence of traditional methods for preparing oriented fiber membranes on electrospinning technology, realizes dry film forming technology, and has great application prospect.

Description

Technical Field

[0001] This invention relates to the field of fiber membrane preparation technology, and in particular to a universally applicable method and apparatus for preparing oriented nanofiber membranes. Background Technology

[0002] Currently, oriented fiber membranes have wide applications in thermoelectricity, tissue engineering materials, simulation, energy, and smart wearables. Studies have shown that when applied to thermoelectric applications, the orientation of oriented fiber membranes facilitates rapid carrier transport, increasing the thermoelectric power factor by seven times compared to disordered nanofiber membranes. Therefore, the fabrication of oriented fiber membranes has become a research hotspot in this field.

[0003] The existing methods for preparing oriented nanofiber membranes are mostly electrospinning. For example, the invention patent (application number CN201710601626.1) discloses an orientation bundling device, electrospinning equipment, and a method for preparing nanofiber yarns. This method and device integrates spinning, fiber orientation, fiber transfer, coagulation, twisting, drafting, and winding, and can continuously prepare oriented nanofiber yarns. By using one or even multiple needleless spinnerets, multiple jets are generated simultaneously, increasing the output of electrospinning. Furthermore, the high-speed rotation of the negative pressure fiber collecting roller and the negative pressure airflow at the surface pores are used to make the generated nanofibers highly oriented, realizing the continuous and large-scale production of nanofiber yarns. The invention patent (application number CN201510093616.2) discloses a polyvinylidene fluoride oriented piezoelectric fiber membrane and its preparation method. The polyvinylidene fluoride fiber membrane is prepared by electrospinning and the oriented piezoelectric fiber membrane is received by a high-speed rotating disk. The prepared polyvinylidene fluoride fiber membrane has a high β crystal content and excellent piezoelectric properties.

[0004] The aforementioned methods for preparing oriented fiber membranes all require integration with electrospinning, necessitating specific and complex preparation equipment and processes. They also require a separate rotating device to receive the fiber filaments and orient them. Therefore, these methods suffer from high costs, long processing times, and low versatility due to their dependence on electrospinning, limiting their application scope. Furthermore, preparing nanofiber membranes of different materials requires different initial solutions, leading to changes in instrument parameters and hindering further improvements in production efficiency.

[0005] In view of this, it is necessary to design an improved method and apparatus for universally preparing oriented nanofiber membranes to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a universal method and apparatus for preparing oriented nanofiber membranes. The method involves first freezing polymer nanofibers, then placing them in a heat-insulated, sealed container. Under high-speed shear force, the nanofibers are oriented and screened. Centrifugal force is then applied to the nanofibers, causing them to adhere to a substrate on the inner wall of the container, thus preparing an oriented nanofiber membrane. This method is applicable to polymer nanofibers of different materials, and the preparation process does not require the preparation of a slurry, which accelerates the product manufacturing cycle and reduces production costs. Simultaneously, it separates the fiber spinning and orientation processes, overcoming the dependence of traditional oriented fiber membranes on electrospinning technology and achieving dry film formation technology, which has great application potential.

[0007] To achieve the above-mentioned objective, this invention provides a universally applicable method for preparing oriented nanofiber membranes, comprising the following steps:

[0008] S1. Pre-treat the polymer nanofibers and freeze them with liquid nitrogen for 15-20 min; the diameter of the polymer nanofibers is 100 nm to 6 μm.

[0009] S2. The substrate used for preparing the oriented nanofiber membrane is cleaned and attached to the inner wall of the sealed container of the apparatus for preparing the oriented nanofiber membrane; the apparatus has a high-speed rotation function, and the sealed container includes a rotating component.

[0010] S3. The polymer nanofibers treated in step S1 are placed in the sealed container in step S2 and rotated at high speed for 20 to 180 seconds.

[0011] S4. Remove the substrate from the inner wall of the sealed container and composite oriented polymer nanofibers on its surface to obtain the oriented nanofiber membrane.

[0012] As a further improvement of the present invention, in step S3, the sealed container maintains its internal temperature below -10°C during high-speed rotation to maintain the frozen state of the polymer nanofibers inside.

[0013] As a further improvement of the present invention, the surface roughness of the substrate is 10-100 nm, preferably 70 nm.

[0014] As a further improvement of the present invention, the polymer nanofibers include one or more of polyvinyl alcohol-polyethylene copolymer, nylon and its derivatives, and polypropylene nanofibers; the diameter of the polymer nanofibers is 200-300 nm.

[0015] As a further improvement of the present invention, the substrate includes one of a metal film substrate and a polymer film substrate; the polymer film substrate includes one of a polypropylene film, a polyurethane film, a polyvinyl chloride film, a polystyrene film, and a polyethylene terephthalate film.

[0016] As a further improvement of the present invention, in step S1, the polymer nanofibers are pretreated by immersing them in a crosslinking agent.

[0017] As a further improvement of the present invention, in step S3, the rotational speed of the high-speed rotation is greater than 30,000 rpm, preferably 35,000 rpm.

[0018] An apparatus for universally preparing oriented nanofiber membranes includes a sealed container and a power system. The sealed container contains a rotating component, and the power system provides power to the rotating component. The rotating component includes at least one layer of planar rotating blades and at least one layer of inclined rotating blades with the same tilt angle. A substrate for preparing the oriented nanofiber membrane is attached to the inner wall of the sealed container, and polymer nanofibers frozen in liquid nitrogen are placed in the sealed container. After high-speed rotation, the substrate is removed to obtain the oriented nanofiber membrane.

[0019] As a further improvement of the present invention, the number of blades of the single-layer inclined rotating blade is 1 to 3, and the tilt angle is 20° to 60°; the thickness of the planar rotating blade and the inclined rotating blade is 0.5 to 3.0 μm, preferably 2.0 μm.

[0020] As a further improvement of the present invention, the apparatus for universally preparing oriented nanofiber membranes further includes a heat preservation system for maintaining the temperature of the sealed container.

[0021] The beneficial effects of this invention are:

[0022] 1. This invention discloses a universal method and apparatus for preparing oriented nanofiber membranes. First, polymer nanofibers are pretreated and frozen with liquid nitrogen to achieve a certain degree of hardness. Then, a substrate for preparing the oriented nanofiber membrane is attached to the inner wall of a sealed container of the apparatus. This apparatus has a high-speed rotation function, and the sealed container includes a rotating component. The frozen polymer nanofibers are then placed in the sealed container and rotated at high speed. Finally, the substrate is removed from the inner wall of the sealed container, revealing the oriented polymer nanofibers on its surface, thus obtaining the oriented nanofiber membrane. This method is applicable to polymer nanofibers of different materials, and the preparation process does not require the preparation of a slurry, which accelerates the product manufacturing cycle and reduces the product manufacturing cost. Simultaneously, it separates the fiber spinning and orientation processes, overcoming the dependence of traditional oriented fiber membranes on electrospinning technology, and realizing dry film formation technology, which has great application prospects.

[0023] 2. This invention involves freezing flexible polymer nanofibers to impart a certain degree of rigidity and brittleness, allowing them to break and be oriented under high-speed shear force. Then, under centrifugal force, they adhere to a substrate on the wall of a container, thus producing an oriented nanofiber membrane. The polymer nanofibers in the oriented nanofiber membrane are primarily bonded to the substrate through van der Waals forces. Furthermore, after the membrane is removed from the device, its temperature rises, causing the molecular chains within the nanofibers to enter a "thawing" state. This enhances the movement of the molecular chains, increases the activity of side groups and functional groups, and generates interaction forces with the substrate, further improving the bonding force between the nanofibers and the substrate. This results in an oriented nanofiber membrane with excellent mechanical properties, significantly improving its practicality and application value.

[0024] 3. This invention controls the diameter of the polymer nanofibers and the thickness of the rotating blades to generate strong shear force on the nanofibers, providing sufficient power for their orientation and the composite substrate. By controlling the high-speed rotation time and speed, the length of the fibers after breakage, as well as the thickness and properties of the resulting oriented nanofiber membrane, are controlled. This avoids problems such as excessive processing time, overheating of the device causing the nanofibers to lose their rigidity, leading to blade entanglement, insufficient orientation and centrifugal power, and uneven fiber membrane production. Furthermore, this invention increases the bonding force between the substrate and the polymer nanofibers and improves the surface uniformity of the prepared membrane material by controlling the roughness of the substrate.

[0025] 4. In the universally applicable apparatus for preparing oriented nanofiber membranes of the present invention, the rotating component includes at least one layer of planar rotating blades and at least one layer of inclined rotating blades at the same tilt angle. The planar rotating blades break up agglomerated, elongated polymer nanofibers into short fibers, while the inclined rotating blades are responsible for stirring and sieving the nanofibers, and providing high-speed shear force to the broken short fibers, causing them to orient and adhere to a substrate, thus obtaining an oriented nanofiber membrane. This apparatus is simple in structure and easy to operate, requiring no adaptation to spinning equipment. Combined with the preparation process of the present invention, it can efficiently prepare oriented nanofiber membranes of different materials, providing new equipment and new ideas for the existing preparation of oriented membranes. Attached Figure Description

[0026] Figure 1 This is an electron microscope image of the oriented nanofiber membrane prepared in Example 1 of the present invention.

[0027] Figure 2 This is an electron microscope image of the nylon 6 copolymer nanofiber membrane prepared according to the present invention.

[0028] Figure 3 This is an electron microscope image of the polypropylene copolymer nanofiber membrane prepared according to the present invention.

[0029] Figure 4 The infrared spectra of the oriented nanofiber membranes prepared in Examples 1-3 of this invention are shown.

[0030] Figure 5 This is a schematic diagram illustrating the structure and principle of the universally applicable device for preparing oriented nanofiber membranes according to the present invention.

[0031] Figure Labels

[0032] 1-Sealed container; 2-Rotating assembly; 21-Plane rotating blade; 22-Inclined rotating blade. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0035] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0036] A universally applicable method for preparing oriented nanofiber membranes includes the following steps:

[0037] S1. Pre-treat the polymer nanofibers and freeze them with liquid nitrogen for 15–20 min. The diameter of the polymer nanofibers is 100 nm–6 μm. If the fiber diameter is too large, the prepared material will lack orientation. During the experiment, it was found that an orientation film could not be prepared when the diameter of the silk fibers was 8 μm. The preferred diameter of the polymer nanofibers is 200–300 nm. By controlling the diameter of the polymer nanofibers and coordinating it with the thickness of the rotating blades, the rotating blades exert a strong shear force on the nanofibers, providing sufficient power for their orientation and the composite substrate.

[0038] S2. The substrate used to prepare the oriented nanofiber membrane is cleaned and attached to the inner wall of the sealed container 1 of the apparatus for preparing the oriented nanofiber membrane; the apparatus has a high-speed rotation function and the sealed container includes a rotating component 2.

[0039] S3. The polymer nanofibers treated in step S1 are placed in the sealed container 1 of step S2 and rotated at high speed for 20-180 seconds. The rotation speed is greater than 30,000 rpm, preferably 35,000 rpm. By adjusting the time and speed of high-speed rotation, the length of the fibers after breakage and the thickness and properties of the resulting oriented nanofiber membrane can be controlled. This avoids the problem of not being able to form a film due to too short a treatment time, and also avoids the problem of substrate falling off due to overheating of the device due to too long a treatment time. It also prevents the nanofibers from maintaining a rigid state under freezing conditions.

[0040] S4. Remove the substrate from the inner wall of the sealed container 1 and composite the oriented polymer nanofibers on its surface to obtain the oriented nanofiber membrane.

[0041] Specifically, in step S3, during the high-speed rotation of the sealed container 1, its internal temperature is maintained below -10°C to keep the polymer nanofibers inside in a frozen state. Below -10°C, the fibers remain brittle and less prone to entanglement. Because polymer nanofibers are in a flexible aggregated state at room temperature, directly placing them in the sealed container 1 can lead to problems such as leaf adhesion, insufficient orientation and centrifugal force, and uneven fiber membrane formation, thus failing to successfully produce an oriented nanofiber membrane. Therefore, this invention freezes the flexible polymer nanofibers, giving them a certain degree of rigidity and brittleness, allowing them to break and oriented under high-speed shear force, and then adhere to the substrate on the container wall under centrifugal force, thus producing an oriented nanofiber membrane.

[0042] In this invention, the polymer nanofibers in the oriented nanofiber membrane are mainly bonded to the substrate by van der Waals forces. In addition, after the oriented nanofiber membrane is taken out of the sealed container 1 of the device, its temperature rises, causing the molecular chain segments inside the nanofibers to be in a "thawing" state. That is, the movement of the molecular chains is enhanced, the activity of side groups and functional groups is increased, and interaction forces are generated with the substrate, which further improves the bonding force between the nanofibers and the substrate. This results in the oriented nanofiber membrane having excellent mechanical properties, improving its practicality and application value.

[0043] Specifically, the surface roughness of the substrate is 10–100 nm. Controlling the roughness of the substrate increases the bonding force between it and the polymer nanofibers, as well as the uniformity of the prepared membrane material surface. Excessive surface roughness of the substrate will affect the membrane surface uniformity. The polymer nanofibers include one or more of polyvinyl alcohol-polyethylene copolymer, nylon and its derivatives, and polypropylene nanofibers. The substrate includes one of a metal membrane substrate and a polymer membrane substrate; the polymer membrane substrate is selected from polymer membranes with a surface roughness of 10–100 nm that do not react with the nanofibers, including one of polypropylene membranes, polyurethane membranes, polyvinyl chloride membranes, polystyrene films, and polyethylene terephthalate films.

[0044] In some specific embodiments, in addition to achieving oriented film formation of polymer nanofibers, they can also be used for materials that are not easily achieved by traditional spray film methods. For example, carbon nanotubes and nanofibers can be blended into a film by simply placing the carbon nanotubes and polymer nanofibers in a sealed container to achieve physical blending and obtain a carbon nanotube-modified oriented nanofiber film.

[0045] In some specific embodiments, in step S1, the polymer nanofibers are pretreated by immersing them in a crosslinking agent; this can improve the bonding strength between the polymer nanofibers and the substrate.

[0046] Please see Figure 5 As shown, a universally applicable apparatus for preparing oriented nanofiber membranes includes a sealed container 1 and a power system. The sealed container 1 is equipped with a rotating component 2, and the power system provides power to the rotating component 2. The rotating component 2 includes at least one layer of planar rotating blades 21 and at least one layer of inclined rotating blades 22 with the same tilt angle. The substrate for preparing the oriented nanofiber membrane is attached to the inner wall of the sealed container 1, and then polymer nanofibers that have been frozen with liquid nitrogen are placed in the sealed container 1. After high-speed rotation, the substrate is removed to obtain the oriented nanofiber membrane.

[0047] In this universally applicable apparatus for preparing oriented nanofiber membranes, planar rotating blades 21 break down agglomerated, slender polymer nanofibers into short fibers with a length of 2–5 μm. Inclined rotating blades are responsible for stirring and sieving the nanofibers, and providing high-speed shear force to the broken short fibers, causing them to orient and adhere to a substrate, thus obtaining an oriented nanofiber membrane. This apparatus is simple in structure and easy to operate, requiring no adaptation to spinning equipment. Combined with the preparation process of this invention, it can efficiently prepare oriented nanofiber membranes of different materials, providing new equipment and new ideas for the existing preparation of oriented membranes.

[0048] Specifically, the single-layer inclined rotating blade 21 has 1 to 3 blades with an inclination angle of 20° to 60°; the thickness of the planar rotating blade 21 and the inclined rotating blade 22 is 0.5 to 3.0 μm, preferably 2.0 μm. Rotating blades within this thickness range, combined with polymer nanofibers with a diameter range of 100 nm to 6 μm, allow the rotating blades to exert strong shear force on the nanofibers, providing sufficient power for their orientation and the composite substrate, which is beneficial for the preparation of oriented nanofiber membranes.

[0049] exist Figure 5 In the schematic diagram of the universally applicable device for preparing oriented nanofiber membranes, the planar rotating blades 21 have different blade shapes, and the inclined rotating blades 22 are only one layer with only one blade. In practical applications, the shape of the planar rotating blades 21, the number of layers of the inclined rotating blades 22, and the number of blades can be adjusted according to the type and quantity of the fibers being processed.

[0050] In some specific embodiments, the rotating component 2 includes three layers of blades, specifically the uppermost planar rotating blade 21, the middle layer, and the lower layer of inclined rotating blades 22; the inclined direction and angle of the inclined rotating blades 22 are consistent, and the angle of inclination of the blades to the horizontal plane is 20°.

[0051] Specifically, the apparatus for universally preparing oriented nanofiber membranes also includes a thermal insulation system, which is used to maintain the temperature of the sealed container 1 to prevent the polymer nanofibers in the frozen state from experiencing flexibility recovery issues.

[0052] Example 1

[0053] This embodiment provides a method and apparatus for universally preparing oriented nanofiber membranes. The specific method includes the following steps:

[0054] S1. Pre-treat polyvinyl alcohol-polyethylene copolymer (PVA-co-PE) nanofibers and freeze them with liquid nitrogen for 20 min; the diameter of the nanofibers is 300 nm.

[0055] S2. The polyurethane substrate used to prepare the oriented nanofiber membrane is cleaned and attached to the inner wall of the sealed container 1 of the apparatus for preparing the oriented nanofiber membrane.

[0056] The surface roughness of the polyurethane substrate is 70 nm; the device used has a high-speed rotation function, and the sealed container 1 includes a rotating component 2, which includes three layers of blades, with the uppermost layer being a planar rotating blade 21, and the middle and lower layers being inclined rotating blades 22; the thickness of all rotating blades is 2.0 μm.

[0057] S3. The polymer nanofibers treated in step S1 are placed in the sealed container 1 of step S2 and rotated at high speed for 30 seconds; the rotation speed is 35000 rpm.

[0058] S4. Remove the substrate from the inner wall of the sealed container 1 and composite oriented PVA-co-PE nanofibers on its surface to obtain a polyvinyl alcohol-polyethylene copolymer nanofiber membrane with an oriented structure.

[0059] Please see Figure 1 The image shown is an electron microscope (EM) image of the polyvinyl alcohol-polyethylene copolymer nanofiber membrane with an oriented structure prepared in Example 1. The image shows that the PVA-co-PE nanofibers exhibit good orientation, indicating the feasibility of the dry film formation technology described in this scheme.

[0060] Examples 2-3

[0061] Examples 2 and 3 provide a universal method for preparing oriented nanofiber membranes. The difference from Example 1 is that the polymerized nanofibers in Examples 2 and 3 are nylon 6 copolymer nanofibers and polypropylene copolymer nanofibers, respectively; the rest are roughly similar to Example 1 and will not be described again here.

[0062] Please see Figures 2-3 As shown, Figure 2 This is an electron microscope image of a nylon 6 copolymer nanofiber membrane. Figure 3 This is an electron micrograph of a polypropylene copolymer nanofiber membrane. From... Figure 2 It can be seen from the above that the nanofiber orientation effect in the nylon 6 copolymer nanofiber membrane is better; Figure 3 The polypropylene copolymer nanofiber membrane exhibits good overall orientation. In the high-magnification image of Figure (a), the fibers show slight disorder, which is due to the entanglement between the polypropylene copolymer nanofibers. However, as can be seen from Figure (b), the overall orientation of the polypropylene copolymer nanofiber membrane is still relatively good.

[0063] Please see Figure 4 As shown, the oriented nanofiber membranes prepared in Examples 1-3 were subjected to infrared spectroscopy analysis, and the results are as follows. Figure 4 As can be seen from the figure, polyvinyl alcohol-polyethylene, nylon 6, and polypropylene copolymer nanofibers are all well composited on the substrate to obtain nanofiber membranes.

[0064] Comparative Example 1

[0065] Comparative Example 1 provides a method for preparing oriented nanofiber membranes. The difference from Example 1 is that the nanofibers were not frozen in step S1. The rest is roughly similar to Example 1 and will not be described again here.

[0066] Examples 4-5

[0067] Examples 4 and 5 provide a universal method for preparing oriented nanofiber membranes. The difference from Example 1 is that the substrates are polyethylene terephthalate (PET) (roughness of 24 nm) and tin foil (roughness of 14 nm), respectively. The rest is roughly similar to Example 1 and will not be described again here.

[0068] In the experiment of Comparative Example 1, because the nanofibers were not frozen, severe entanglement occurred between the fibers and between the fibers and the blade, and the oriented nanofiber membrane was not successfully prepared.

[0069] The thickness and mechanical properties of the oriented nanofiber membranes prepared in Examples 1-5 were tested, and the results are shown in the table below.

[0070] Table 1. Test results of thickness and performance of oriented nanofiber membranes in Examples 1-5

[0071] Thickness / mm Tensile strength / MPa Example 1 0.3 110 Example 2 0.3 100 Example 3 0.3 90 Example 4 0.3 250 Example 5 0.3 98

[0072] As shown in Table 1, comparing the test results of Examples 1 to 5, it can be seen that changing the type of polymer nanofibers can affect the tensile strength of the prepared oriented nanofiber membrane; and the tensile strength is mainly affected by the type of substrate.

[0073] Examples 6-9 and Comparative Examples 2-3

[0074] Examples 6-9 and Comparative Examples 2-3 provide a method for preparing oriented nanofiber membranes. Compared with Example 1, the difference lies in the parameters of nanofiber diameter and high-speed rotation time, as shown in the table below. The rest are roughly similar to Example 1 and will not be described again here.

[0075] Table 2 shows the parameter settings for Examples 6-9 and Comparative Examples 2-3.

[0076]

[0077]

[0078] The thickness and mechanical properties of the oriented nanofiber membranes prepared in Examples 6-9 and Comparative Example 3 were tested, and the results are shown in the table below.

[0079] Table 3. Test results of nanofiber membrane thickness and performance in Examples 6-9 and Comparative Example 3.

[0080] Thickness / mm Tensile strength / MPa Example 6 0.3 100 Example 7 0.3 80 Example 8 0.3 110 Example 9 0.3 120 Comparative Example 3 0.3 120

[0081] As shown in Table 3, within a certain range, the smaller the diameter of the polymer nanofibers, the better the orientation effect and the greater the tensile strength of the resulting oriented fiber membrane. Within the allowable range of the device, the longer the rotation time, the higher the tensile strength of the resulting oriented fiber membrane. However, after a certain time, the tensile strength no longer increases.

[0082] In Comparative Example 2, an oriented membrane was prepared using polymer nanofiber membranes with a diameter of 8 μm. It was found that the oriented fiber membrane could not be prepared due to the excessively large fiber diameter. In Comparative Example 3, during the later stages of high-speed rotation of the sealed container 1, the fibers gradually became entangled and stuck to the blade, making it impossible to continue preparing the oriented nanofiber membrane. Therefore, its tensile strength was similar to that of the fiber membrane in Example 9.

[0083] In summary, this invention provides a universal method and apparatus for preparing oriented nanofiber membranes. First, polymer nanofibers are pretreated and frozen with liquid nitrogen to achieve a certain degree of hardness. Then, a substrate for preparing the oriented nanofiber membrane is attached to the inner wall of a sealed container of the apparatus. Next, the frozen polymer nanofibers are placed in the sealed container and rotated at high speed. Finally, the substrate is removed from the inner wall of the sealed container, revealing the oriented polymer nanofibers on its surface, thus obtaining the oriented nanofiber membrane. In the apparatus for preparing the oriented nanofiber membrane, the rotating component includes at least one layer of planar rotating blades and at least one layer of inclined rotating blades at the same angle. The planar rotating blades break up the aggregated, elongated polymer nanofibers into short fibers, while the inclined rotating blades are responsible for stirring and sieving the nanofibers, and providing high-speed shear force to the broken short fibers, causing them to orient and adhere to the substrate, resulting in the oriented nanofiber membrane. This apparatus is simple in structure and easy to operate, requiring no adaptation to spinning equipment. Combined with the preparation process of this invention, it can efficiently prepare oriented nanofiber membranes of different materials. The method of this invention is applicable to polymer nanofibers of different materials, and the preparation process does not require the preparation of slurry, which not only speeds up the product manufacturing cycle but also reduces the product manufacturing cost. At the same time, it realizes the separation of fiber spinning and orientation process, overcomes the dependence of traditional orientation fiber membranes on electrospinning technology, realizes dry film formation technology, and has great application prospects.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for universally preparing oriented nanofiber membranes, characterized in that, Includes the following steps: S1. Pre-treat the polymer nanofibers and freeze them with liquid nitrogen for 15-20 min; the diameter of the polymer nanofibers is 100 nm to 6 μm. S2. Clean the substrate used to prepare the oriented nanofiber membrane and attach it to the inner wall of the sealed container of the apparatus for preparing the oriented nanofiber membrane; the apparatus has a high-speed rotation function, and the sealed container includes a rotating component. S3. The polymer nanofibers treated in step S1 are placed in the sealed container in step S2 and rotated at high speed for 20-180 seconds. S4. Remove the substrate from the inner wall of the sealed container and composite oriented polymer nanofibers on its surface to obtain the oriented nanofiber membrane.

2. The method for universally preparing oriented nanofiber membranes according to claim 1, characterized in that, In step S3, the sealed container maintains its internal temperature below -10°C during high-speed rotation to keep the polymer nanofibers inside in a frozen state.

3. The method for universally preparing oriented nanofiber membranes according to claim 1, characterized in that, The surface roughness of the substrate is 10~100nm.

4. The method for universally preparing oriented nanofiber membranes according to claim 1, characterized in that, The polymer nanofibers include one or more of polyvinyl alcohol-polyethylene copolymer, nylon and its derivatives, and polypropylene nanofibers; the diameter of the polymer nanofibers is 200~300nm.

5. The method for universally preparing oriented nanofiber membranes according to claim 1, characterized in that, The substrate includes one of a metal film substrate and a polymer film substrate; the polymer film substrate includes one of a polypropylene film, a polyurethane film, a polyvinyl chloride film, a polystyrene film, and a polyethylene terephthalate film.

6. The method for universally preparing oriented nanofiber membranes according to claim 1, characterized in that, In step S1, the polymer nanofibers are pretreated by immersing them in a crosslinking agent.

7. The method for universally preparing oriented nanofiber membranes according to claim 1, characterized in that, In step S3, the high-speed rotation speed is greater than 30,000 rpm.

8. The method for universally preparing oriented nanofiber membranes according to claim 7, characterized in that, The high-speed rotation speed is 35,000 rpm.

9. An apparatus for universally preparing oriented nanofiber membranes, characterized in that, The device includes a sealed container and a power system. The sealed container contains a rotating component, and the power system provides power to the rotating component. The rotating component includes at least one layer of planar rotating blades and at least one layer of inclined rotating blades. The substrate for preparing the oriented nanofiber membrane is attached to the inner wall of the sealed container, and then the polymer nanofibers that have been frozen by liquid nitrogen are placed in the sealed container. After high-speed rotation, the substrate is removed to obtain the oriented nanofiber membrane. The single-layer inclined rotating blade has 1 to 3 blades, with an inclination angle of 20° to 60°; the thickness of the planar rotating blade and the inclined rotating blade is 0.5 to 3.0 µm.

10. The apparatus for universally preparing oriented nanofiber membranes according to claim 9, characterized in that, The thickness of the planar rotating blade and the inclined rotating blade is 2.0µm.

11. The apparatus for universally preparing oriented nanofiber membranes according to claim 9, characterized in that, The apparatus for universally preparing oriented nanofiber membranes further includes a thermal insulation system for maintaining the temperature of the sealed container.

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