A method for controllable preparation of magnetic nanofiber film by current-controlled magnetic field-assisted electrospinning

Abstract

A method for controllably preparing magnetic nanofiber films using current-controlled magnetic field-assisted electrospinning involves dissolving PAN white powder in DMF organic solvent, continuously stirring with a magnetic field, and then ultrasonically dispersing the solution using an ultrasonic cleaner to prepare a uniformly dispersed PAN / DMF solution. Fe3O4 nanoparticles and an equal amount of dispersant Triton X-100 are then added to the prepared solution, followed by ultrasonic dispersion to form a uniformly dispersed magnetic electrospinning solution. The prepared magnetic electrospinning solution is then used to prepare fine and uniform high-performance magnetic nanofiber samples using a controllable magnetic field-assisted electrospinning device generated by a current-controlled electromagnetic lens. These samples are then dried in a drying oven to obtain a high-performance magnetic nanofiber film with reduced deposition area, increased thickness, enhanced mechanical properties, improved magnetic properties, and a smaller and more uniform average nanofiber diameter.

Description

Technical Field

[0001] This invention belongs to the technical field of functional nanofiber manufacturing, and particularly relates to a method for controllable preparation of magnetic nanofiber films by current-controlled magnetic field-assisted electrospinning. Background Technology

[0002] Electrospinning, as a highly efficient and flexible nanofiber fabrication process, has demonstrated enormous application potential in various fields such as materials science, biomedicine, and environmental protection. Traditional electrospinning technology primarily relies on an electric field to stretch and refine the spinning solution, forming nanofibers. However, during the spinning process, the arrangement and deposition of fibers are often influenced by various factors such as electric field distribution, spinning solution properties, and environmental parameters, resulting in disordered fiber arrangement, uneven diameter distribution, and difficulty in achieving ordered arrangement on a macroscopic scale. These problems limit the application of nanofibers in high-end fields, such as high-performance composite materials and biomedical implants.

[0003] To overcome the limitations of traditional electrospinning technology, researchers have begun to explore the introduction of magnetic fields into the electrospinning process. Magnetic field-assisted electrospinning (MFES) technology applies a magnetic field to the spinning region, utilizing the attraction and repulsion of the magnetic field on charged fibers to achieve precise control over fiber arrangement and deposition. This method can not only improve fiber orderliness but also control fiber diameter and morphology, thereby producing nanofibers with excellent properties and specific structures. However, existing MFES techniques still have some problems. Chinese invention patent CN118029620A discloses a high flame-retardant and corrosion-resistant fiberglass asphalt shingle and its preparation method, in which the fiberglass asphalt shingle is prepared using magnetic field-assisted electrospinning technology generated by a magnet. Chinese invention patent CN113897690A discloses a method for preparing ordered PVDF nanofibers based on magnetic field-assisted electrospinning, which also uses magnetic field-assisted electrospinning generated by a magnet. Chinese invention patent CN103060933B discloses a method for preparing polymer micro / nano composite fibers, which involves adding magnetic nanoparticles and using a magnetic field generated by a magnet to assist in the preparation of nanofibers. While the magnetic field generated by a magnet can influence fiber alignment and deposition during electrospinning to some extent, this method still exhibits several significant drawbacks in practical applications. First, the strength and distribution of the magnetic field generated by the magnet are often difficult to achieve ideal conditions. Due to the physical limitations of magnets, the strength and uniformity of the generated magnetic field may not meet the requirements for precise fiber control during electrospinning. Second, the stability and controllability of the magnetic field are poor; the magnetic field strength is easily affected by ambient temperature, humidity, and other surrounding magnetic field sources, leading to fluctuations in fiber orientation and deposition patterns during the spinning process. Finally, the range of the magnetic field generated by the magnet is limited and may not cover the entire preparation area. This necessitates frequent adjustments to the position and number of magnets during the preparation process, increasing operational complexity and potentially affecting preparation efficiency. Chinese patent ZL201020033366.6 proposes adding an adjustable magnetic field to the polymer jet stretching process to improve the crystallization behavior of polymers and make up for the shortcomings of low crystallinity and poor mechanical strength of traditional electrospun fibers. However, the magnetic field adjustment in this patent is still adjusted by moving a sliding magnet up and down and horizontally on the support to adjust the magnetic field strength. This manual adjustment method is relatively cumbersome and has limited adjustment accuracy. Due to its physical characteristics (such as magnetization intensity and size), the sliding magnet is difficult to generate a high-intensity or rapidly changing uniform magnetic field, which may cause the polymer jet to be subjected to uneven magnetic force during the stretching process, thus affecting the fiber quality.

[0004] In summary, while magnetic field-assisted electrospinning technology shows promise in improving fiber performance, existing magnetic fields are primarily generated by magnets. This method suffers from limitations in magnetic field strength and uniformity, poor stability and controllability, and a limited magnetic field range, thus affecting the precise control and efficiency of fiber preparation. Therefore, developing more efficient, stable, and controllable magnetic field adjustment techniques is crucial for advancing magnetic field-assisted electrospinning technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and to design a method for controllable preparation of magnetic nanofiber films using current-controlled magnetic field-assisted electrospinning. This invention employs an advanced current-controlled magnetic field-assisted electrospinning device, which flexibly controls the magnetic field strength by precisely adjusting the current, thereby achieving a dual effect during the electrospinning process: firstly, enhancing the electron aggregation effect on the surface of the charged jet during electrospinning; secondly, effectively guiding the directional alignment of magnetic nanoparticles. This invention not only significantly improves the overall stability and controllability of electrospinning technology but also greatly optimizes the accuracy and efficiency of nanofiber film preparation, opening up new avenues for the large-scale, high-quality production of magnetic nanofibers.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for controllably preparing magnetic nanofiber films via current-controlled magnetic field-assisted electrospinning includes the following steps:

[0008] Step (1) Preparation of spinning solution: Weigh polyacrylonitrile (PAN) powder and dissolve it in N,N-dimethylformamide (DMF) organic solvent. Stir continuously with magnetic force, and then use an ultrasonic cleaner to ultrasonically disperse the solution to prepare a uniformly dispersed PAN / DMF solution. Then add Fe3O4 nanoparticles and an equal amount of dispersant Triton X-100 to the prepared solution, and then perform ultrasonic dispersion to form a uniformly dispersed magnetic electrospinning solution.

[0009] Step (2) Device adjustment: Securely fix the syringe on the micro-injection pump, adjust the distance between the syringe needle and the collecting electrode, and the distance between the electromagnetic lens and the collecting electrode. Then connect the positive power line of the DC high voltage power supply to the syringe and the negative power line to the collecting electrode. Set the injection rate of the micro-injection pump and the current of the electromagnetic lens to 1A. Finally, turn on the DC high voltage power supply.

[0010] Step (3) Preparation of nanocomposite fibers: As the micro-injection pump is started, the prepared magnetic PAN / DMF / Fe3O4 magnetic electrospinning solution gathers at the syringe needle. Under the combined action of the high voltage electrostatic field force and the controllable magnetic field force generated by the electromagnetic lens, the droplet forms a charged jet that is transferred to the collecting electrode, and the magnetic nanofiber film can be prepared in a controllable manner.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] (1) This invention employs current regulation technology, which enables precise adjustment of the magnetic field. By adjusting the magnitude and direction of the current, the strength and direction of the magnetic field can be precisely controlled, thereby meeting the precise requirements for fiber arrangement, deposition, and magnetic properties during electrospinning.

[0013] (2) Improved magnetic field stability and controllability. Compared with the traditional method of generating magnetic fields with magnets, the magnetic field controlled by current has higher stability and controllability. It is not easily affected by ambient temperature, humidity and external magnetic field sources, and can ensure the stable output of magnetic field strength during spinning, thereby improving the stability of fiber orientation and deposition mode.

[0014] (3) The magnetic field range is expanded and uniform. The magnetic field generated by the present invention through current regulation can cover the entire preparation area, and the magnetic field distribution is uniform. This avoids the need to frequently adjust the position and number of magnetic field generating devices, simplifies the preparation process, improves preparation efficiency, and ensures the uniformity and consistency of fibers throughout the spinning area.

[0015] (4) Optimization of magnetic nanofiber properties. By precisely controlling the magnetic field, this invention can prepare nanofibers with excellent magnetic properties. The magnetic field generated by the electromagnetic lens can reduce the average diameter of magnetic nanofibers prepared by electrospinning PAN / DMF / Fe3O4 spinning solution by 5.1%, increase the average thickness by 92%, improve mechanical properties by 19.3%, and increase saturation magnetization by 56.5%. The magnetic parameters of these fibers, such as saturation magnetization, coercivity, and remanence, can be significantly improved, thus showing broad application prospects in magnetic recording materials, magnetic sensors, biomedicine, and other fields. Attached Figure Description

[0016] Figure 1 This is a diagram of an apparatus used in the present invention for a method of controllable preparation of magnetic nanofiber thin films by current-controlled magnetic field-assisted electrospinning.

[0017] Figure 2 These are electron microscope (SEM) images of magnetic nanofiber films prepared under four different experimental conditions: with and without magnetic spinning solution and with and without electromagnetic lens, as described in this invention patent.

[0018] Figure 3The images are transmission electron microscope (TEM) images of magnetic nanofiber films prepared under experimental conditions with magnetic spinning solution and electromagnetic lens, as described in this invention patent.

[0019] Figure 4 The graph shows the average diameter of nanofibers prepared under four different experimental conditions: with and without magnetic spinning solution and with and without electromagnetic lens, as described in this invention patent.

[0020] Figure 5 The graph shows the average thickness of nanofibers prepared under four different experimental conditions: with and without magnetic spinning solution and with and without electromagnetic lens, as described in this invention patent.

[0021] Figure 6 The graph shows the mechanical properties of nanofibers prepared under four different experimental conditions: with and without magnetic spinning solution and with and without electromagnetic lens, as described in this invention patent.

[0022] Figure 7 The graph shows the magnetic properties of nanofibers prepared under four different experimental conditions: with and without magnetic spinning solution and with and without electromagnetic lens, as described in this invention patent. Detailed Implementation

[0023] The present invention will be further described below with reference to embodiments and accompanying drawings. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0024] like Figure 1As shown, a current-controlled magnetic field-assisted electrospinning device for preparing magnetic nanofiber films includes an electromagnetic lens 1, an electromagnetic lens power supply 2, a positive line 3 of the electromagnetic lens power supply, a negative line 4 of the electromagnetic lens power supply, a syringe 5, a syringe needle 6, a micro-injection pump 7, a DC high-voltage power supply 8, a DC high-voltage power supply positive line 9, a DC high-voltage power supply negative line 10, a collecting electrode 11, a magnetic nanofiber jet 12, and a magnetic nanofiber film 13. The electromagnetic lens 1 is positioned between the syringe 5 and the collecting electrode 11, with a distance of 8 cm between them. Power is supplied via the positive line 3 and the negative line 4 of the electromagnetic lens power supply, and the magnitude of the current is adjusted to control the strength of the magnetic field generated by the electromagnetic lens 1. The positive line 9 of the DC high-voltage power supply 8 is connected to the syringe needle 6, and the negative line 10 of the DC high-voltage power supply is connected to the collecting electrode 11, which is grounded. The syringe 5, under the action of the micro-injection pump 7, gathers the magnetic spinning solution on the syringe needle 6. The magnetic spinning solution droplet becomes a charged jet under the action of the DC high voltage power supply 8. Then, under the action of the magnetic field generated by the electromagnetic lens 1, the trajectory of the magnetic nanofiber jet 12 is changed, and finally falls on the collecting electrode 11 to form a magnetic nanofiber film 13.

[0025] A method for controllably preparing magnetic nanofiber films via current-controlled magnetic field-assisted electrospinning includes the following steps:

[0026] Step (1) Preparation of spinning solution: Weigh polyacrylonitrile (PAN) powder and dissolve it in N,N-dimethylformamide (DMF) organic solvent. Stir continuously with magnetic force, and then use an ultrasonic cleaner to ultrasonically disperse the solution to prepare a uniformly dispersed PAN / DMF solution. Then add Fe3O4 nanoparticles and an equal amount of dispersant Triton X-100 to the prepared solution, and then perform ultrasonic dispersion to form a uniformly dispersed magnetic electrospinning solution.

[0027] The mass ratio of Fe3O4 nanoparticles to PAN powder is 1:0.2.

[0028] Step (2) Device adjustment: Securely fix the syringe on the micro-injection pump and adjust it so that the distance between the syringe needle and the collecting electrode is 16cm and the distance between the electromagnetic lens and the collecting electrode is 8cm. Then connect the positive line of the DC high voltage power supply to the syringe and the negative line to the collecting electrode. Set the injection rate of the micro-injection pump to 0.8mL / h, turn on the electromagnetic lens and adjust the current to 1A. Finally, turn on the DC high voltage power supply and set the voltage to 15Kv, so as to form a high voltage electric field between the syringe needle and the collecting electrode, and introduce a magnetic field between the two through the electromagnetic lens device. The device adjustment is completed.

[0029] Step (3) Preparation of nanocomposite fibers: As the micro-injection pump is started, the prepared spinning solution magnetic PAN / DMF / Fe3O4 spinning solution gathers at the syringe needle. Under the combined action of the high voltage electrostatic field force and the controllable magnetic field force generated by the electromagnetic lens, the droplets form a charged jet that is transferred to the collecting electrode, and PAN / Fe3O4 magnetic nanofibers can be prepared in a controllable manner.

[0030] The electromagnetic lens of this invention has an inner diameter of 188mm, an excitation coil of 1360 turns, and a current of 1A.

[0031] The spinning time of this invention is 2 hours, the spinning temperature is 25°C, and the spinning humidity is 40%.

[0032] The technical solution of the present invention will be further described below with reference to the embodiments:

[0033] Example 1:

[0034] In this embodiment, the current of the electromagnetic lens was set to 0A, and a PAN / DMF spinning solution without Fe3O4 nanoparticles was prepared. Nanofiber films were prepared under the parameters of electrospinning voltage of 15Kv, distance between needle and collecting electrode of 16cm, and feed rate of 0.8mL / h for 2 hours.

[0035] Example 2:

[0036] In this embodiment, the current of the electromagnetic lens was set to 1A, and a PAN / DMF spinning solution without Fe3O4 nanoparticles was prepared. Nanofiber films were prepared under the following parameters: electrospinning voltage of 15KV, distance between needle and collecting electrode of 16cm, distance between electromagnetic lens and collecting electrode of 8cm, and needle advance rate of 0.8mL / h for 2 hours.

[0037] Example 3:

[0038] In this embodiment, the current of the electromagnetic lens was set to 0A, and a PAN / DMF / Fe3O4 spinning solution containing Fe3O4 nanoparticles was prepared. Magnetic nanofiber films were prepared under the conditions of electrospinning parameters of 15KV voltage, 16cm distance between the needle and the collecting electrode, and 0.8mL / h feed rate for 2 hours.

[0039] Example 4:

[0040] In this embodiment, the current of the electromagnetic lens was set to 1A, and a PAN / DMF / Fe3O4 spinning solution containing Fe3O4 nanoparticles was prepared. Magnetic nanofiber films were prepared under the following electrospinning parameters: voltage 15KV, distance between needle and collecting electrode 16cm, distance between electromagnetic lens and collecting electrode 8cm, and feed rate 0.8mL / h, for a time of 2 hours.

[0041] The fibers prepared in Examples 1-4 above were characterized by SEM, and the nanofiber diameter, nanofiber film thickness, deposition circle area, mechanical properties, and magnetic properties were tested.

[0042] (1) SEM characterization: The morphology of nanofibers prepared under four different experimental conditions (with and without magnetic spinning solutions, and with and without electromagnetic lenses) in Examples 1-4 was observed using an S-4800 SEM at 5.0 kV and magnification of 5.0x. The diameter of 40 nanofibers prepared under each of the four conditions was measured using ImageJ. Figure 2 The image shows SEM images of nanofibers prepared under four different experimental conditions: with and without magnetic spinning solutions and with and without electromagnetic lenses. Figure 2 Image a in the middle is a SEM image of nanofibers prepared under conditions of non-magnetic spinning solution and no electromagnetic lens. Figure 2 Image b in the image is a SEM image of nanofibers prepared under conditions of magnetic spinning solution and without an electromagnetic lens. Figure 2 Image c shows the SEM images of nanofibers prepared under conditions of non-magnetic spinning solution and electromagnetic lens. Figure 2 Image d shows a SEM image of nanofibers prepared under conditions of magnetic spinning solution and electromagnetic lens. From... Figure 2 As can be seen, without the use of an electromagnetic lens, the fibers appear sparse and coarse overall, while with the use of an electromagnetic lens, the nanofibers appear denser, more uniform, and finer. The average diameter of the nanofibers is shown in the figure. Figure 4 As shown, under non-magnetic spinning solution conditions, the magnetic field generated by the electromagnetic lens can controllably reduce the average diameter of the prepared nanofibers by 6.0%, while under magnetic spinning solution conditions, the magnetic field generated by the electromagnetic lens can controllably reduce the average diameter of the prepared magnetic nanofibers by 19.2%. This demonstrates that regardless of whether the spinning solution contains magnetic nanoparticles, the electromagnetic lens has a focusing effect on the charged jets from electrospun electrospun fibers, and the effect is more pronounced on charged jets containing magnetic nanoparticles.

[0043] (2) TEM characterization: The morphology of the nanofibers prepared under the conditions of magnetic spinning solution and electromagnetic lens in Example 4 was observed using TEM, such as... Figure 3 As shown, this indicates that magnetic nanoparticles have been successfully doped into nanofibers. Figure 3 Nanofibers prepared under conditions of magnetic spinning solution and electromagnetic lens: a is a TEM image at the 500 nm scale; b is a TEM image at the 100 nm scale.

[0044] (3) Thickness testing: The thickness of the nanofiber films prepared under four different experimental conditions (without / without magnetic spinning solution and without / without electromagnetic lens) in Examples 1-4 was tested using a thickness gauge. Ten tests were performed on each sample under each experimental condition, and the average value was taken. Figure 5The figure shows the average thickness of nanofiber films prepared under four different experimental conditions: with and without magnetic spinning solution, and with and without electromagnetic lenses. Comparison reveals that in Examples 1 (thickness 160.71 μm) and 3 (thickness 169.80 μm), no electromagnetic lens was used, resulting in thinner nanofiber films. In Examples 2 (thickness 200.01 μm) and 4 (thickness 326.50 μm), when nanofibers were prepared by electrospinning with electromagnetic lens assistance, magnetic nanoparticles were present in the electrospinning ribbon jet. The magnetic field generated by the electromagnetic lens not only aggregated electrons on the surface of the electrospinning ribbon jet but also guided the magnetic nanoparticles, allowing for further control of the nanofibers and leading to a further increase in thickness.

[0045] (4) Measurement of deposition circle area: The deposition circle area of ​​the nanofiber films prepared under four different experimental conditions (without / with magnetic spinning solution and without / with electromagnetic lens) in Examples 1-4 was measured and calculated using measurement methods. It was found that the deposition circle area of ​​Example 1 was 414.690 cm². 2 Example 3 and Example 4 (deposition circle area is 343.219 cm²) 2 No electromagnetic lens equipment was used in any of the experiments, and the nanofiber thin films prepared under these conditions had a relatively large deposition circle area. Example 2 (deposition circle area: 240.332 cm²) 2 Example 4 and Example 5 (deposition circle area is 164.934 cm²) 2 When preparing nanofibers using electromagnetic lens-assisted electrospinning, the deposition circle area further decreases. This indicates that the magnetic field generated by the electromagnetic lens has a dual effect on the magnetic nanofibers, thereby improving further control over the electrospinning process.

[0046] (5) Mechanical property testing: The mechanical properties of the nanofiber films prepared under four different experimental conditions (without / without magnetic spinning solution and without / without electromagnetic lens) in Examples 1-4 were tested using a computer-controlled tensile stress testing machine. Samples under each experimental condition were tested five times, and the average value was taken. Figure 6 The figure shows the stress-strain values ​​of nanofiber films prepared under four different experimental conditions: with and without magnetic spinning solutions, and with and without electromagnetic lenses. Comparison reveals that in Examples 1 (stress of 2483.86 kPa) and 3 (stress of 911.13 kPa), no electromagnetic lens was used, resulting in nanofiber films with lower mechanical properties. In Examples 2 (stress of 2962.90 kPa) and 4 (stress of 1299.32 kPa), the mechanical properties were further improved when nanofibers were prepared by electrospinning with electromagnetic lens assistance, highlighting the effect of the magnetic field generated by the electromagnetic lens on the electrospun ribbon jet.

[0047] (6) Magnetic property testing: The magnetic properties of the nanofiber films prepared under four different experimental conditions (without / without magnetic spinning solution and without / without electromagnetic lens) in Examples 1-4 were tested using a comprehensive physical property measurement system. The magnetic property values ​​are shown in the figure below. Figure 7 As shown, the spinning solutions in Examples 1 and 2 do not contain magnetic nanoparticles, so their magnetic properties are 0. The saturation magnetization of the nanofibers prepared in Example 3 without using an electromagnetic lens is 1.86 emu / g. The saturation magnetization of the nanofibers prepared in Example 4 using an electromagnetic lens is 2.91 emu / g. This indicates that the electromagnetic lens can further control the trajectory of the electrospun ribbon jet.

[0048] This invention discloses a method for controllably preparing magnetic nanofiber films using current-controlled magnetic field-assisted electrospinning, comprising the following steps: PAN white powder is dissolved in DMF organic solvent, continuously stirred under magnetic field force, and then the solution is ultrasonically dispersed using an ultrasonic cleaner to prepare a uniformly dispersed PAN / DMF solution. Fe3O4 nanoparticles and an equal amount of dispersant Triton X-100 are added to the prepared solution, followed by ultrasonic dispersion to form a uniformly dispersed magnetic electrospinning solution. The prepared magnetic electrospinning solution is then used to prepare fine and uniform high-performance magnetic nanofiber samples using a controllable magnetic field-assisted electrospinning device generated by a current-controlled electromagnetic lens. These samples are then dried in a drying oven to obtain a high-performance magnetic nanofiber film with reduced deposition spherical area, increased thickness, enhanced mechanical properties, improved magnetic properties, and a smaller and more uniform average nanofiber diameter. This method not only promotes the advancement of materials science but also brings unprecedented development opportunities to multiple fields such as information technology, healthcare, environmental protection, and new energy, foreshadowing a more intelligent, green, and sustainable future.

[0049] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for controllably preparing magnetic nanofiber films via current-controlled magnetic field-assisted electrospinning, characterized in that, Includes the following steps: Step (1) Preparation of spinning solution: Weigh out white polyacrylonitrile powder and dissolve it in N,N-dimethylformamide organic solvent. Stir continuously with magnetic force, and then use an ultrasonic cleaner to ultrasonically disperse the solution to prepare a uniformly dispersed polyacrylonitrile / N,N-dimethylformamide solution. Then add Fe3O4 nanoparticles and an equal amount of dispersant Triton X-100 to the prepared solution, and then perform ultrasonic dispersion to form a uniformly dispersed magnetic electrospinning solution. Step (2) Device adjustment: Securely fix the syringe on the micro-injection pump, adjust the distance between the syringe needle and the collecting electrode, and the distance between the electromagnetic lens and the collecting electrode; then connect the positive power line of the DC high voltage power supply to the syringe and the negative power line to the collecting electrode, set the injection rate of the micro-injection pump and the current of the electromagnetic lens; finally turn on the DC high voltage power supply; the inner diameter of the electromagnetic lens is 188mm, the excitation coil in the electromagnetic lens has 1360 turns, the current of the electromagnetic lens is set to 1A; the distance between the electromagnetic lens and the collecting electrode is 8cm. Step (3) Preparation of nanocomposite fibers: As the micro-injection pump is started, the prepared magnetic polyacrylonitrile / N,N-dimethylformamide / Fe3O4 magnetic electrospinning solution gathers at the syringe needle. Under the combined action of the high voltage electrostatic field force and the controllable magnetic field force generated by the electromagnetic lens, the droplet forms a charged jet that is transferred to the collecting electrode, and the magnetic nanofiber film can be prepared in a controllable manner.

2. The method for controllable preparation of magnetic nanofiber thin films by current-controlled magnetic field-assisted electrospinning according to claim 1, characterized in that: The mass ratio of Fe3O4 nanoparticles to polyacrylonitrile powder was 1:0.

2.

3. The method for controllable preparation of magnetic nanofiber thin films by current-controlled magnetic field-assisted electrospinning according to claim 1, characterized in that: The distance between the syringe needle and the collecting electrode is 16cm.

4. The method for controllable preparation of magnetic nanofiber films by current-controlled magnetic field-assisted electrospinning according to claim 1, characterized in that: The parameters for electrospinning assisted by the controllable magnetic field generated by the electromagnetic lens are as follows: electrostatic high voltage of 15Kv, magnetic spinning solution propulsion rate of 0.8mL / h, spinning time of 2h, spinning temperature of 25℃, and spinning humidity of 40%.

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