Thermally anisotropic conductive film

Abstract

The invention relates to a thermally-induced anisotropic conductive film and a preparation technology thereof, and belongs to the technical field of new material preparation. The method comprises the following four steps: (1) preparing VO2 (M) by combining hydrothermal and high-temperature roasting; (2) synthesizing polymethyl methacrylate (PMMA) by a bulk polymerization method; (3) preparing a spinning solution; and (4) preparing the [PMMA] / / [VO2 / PMMA] Janus micro-ribbon array thermally-induced anisotropic conductive film by adopting a two-axis parallel electrospinning technology. When heating is carried out (80 DEG C), the prepared thermally-induced anisotropic conductive film has strong thermally-induced anisotropic conductivity, that is, high thermally-induced anisotropic conductivity is realized through heating. The preparation method is simple and easy to implement, batch production can be achieved, and the novel anisotropic conductive film material has wide application prospects.

Description

Technical Field

[0001] This invention relates to the field of new material preparation technology, specifically to thermally induced anisotropic conductive films and their preparation technology. Background Technology

[0002] Anisotropic conductive films are a novel type of interconnect material for electronic components. They possess conductivity in one direction and insulation in other directions, and have been widely used in electronic packaging, chip mounting, and electrode bonding, attracting considerable attention. Developing novel anisotropic conductive films is of great significance to the development of the electronics industry and other related fields.

[0003] Janus materials refer to materials composed of two chemically distinct components or one chemically distinct component with clearly defined partitioned structures within the same system. These materials possess dual properties such as hydrophilic / hydrophobic, polar / nonpolar, luminescent / conductive, and conductive / insulating properties, making them a cutting-edge and hot research area in materials science. Currently reported Janus nanofibers or Janus microbelts consist of two nanofibers or microbelts with different chemical compositions joined side-by-side, exhibiting two distinct partitioned structures and two or more properties. For example, if one side of a Janus nanofiber or Janus microbelt has luminescent properties and the other side has conductive properties, then this type of Janus nanofiber or Janus microbelt possesses both luminescent and conductive functions. Extensive research has been conducted on Janus nanofibers and Janus microbelts.

[0004] Vanadium dioxide (VO2) is a functional metal oxide material with a strongly correlated electron system and exhibits first-order reversible phase transition characteristics. Around the critical temperature of 68°C, VO2 undergoes a metal-insulator or semiconductor phase transition, abruptly changing from a room-temperature monoclinic phase VO2(M) to a high-temperature rutile tetragonal phase VO2(R). The electrical resistance change before and after the phase transition can be as high as 4–5 orders of magnitude. That is, at room temperature, VO2(M) is an insulator or semiconductor with weak conductivity, while at high temperature (68°C) it transforms into a metallic tetragonal phase VO2(R) with strong metallic conductivity, making it a conductive material with thermally induced phase transition characteristics. VO2 also modulates the transmission of infrared light before and after the phase transition, changing from high transmittance at low temperatures to high reflectivity at high temperatures. It is precisely because of these near-room-temperature electrical and optical abrupt changes that VO2 has attracted widespread attention, making it extremely promising for applications in energy-saving color-changing smart windows, photoelectric switches, photoelectric storage, infrared laser radiation protection, uncooled infrared detectors, high-performance batteries, supercapacitors, temperature sensors, and gas sensors. This invention utilizes VO2, which has thermally induced phase change properties, as a conductive material to construct a novel thermally induced anisotropic conductive film.

[0005] Polymethyl methacrylate (PMMA) is a commonly used polymer material with excellent properties. If PMMA and VO2 are mixed to prepare microribbons, serving as one side of a Janus microribbon, and the PMMA microribbon is used as the other side, a [PMMA] / / [VO2 / PMMA] Janus microribbon can be formed. Using these Janus microribbons as building blocks, and employing a special device to orient them, a Janus microribbon array film can be obtained. Within the building block [PMMA] / / [VO2 / PMMA] Janus microribbon... In the structure, one side is a pure PMMA microribbon, which is an insulator and non-conductive at both room temperature and high temperature. The other side is a VO2 / PMMA microribbon. At room temperature, the weak conductivity of VO2 results in weak conductivity on the VO2 / PMMA microribbon side. Thus, for a single Janus microribbon, at room temperature, the VO2 / PMMA microribbon side exhibits weak conductivity along its length at room temperature. However, in the direction perpendicular to the length of the Janus microribbon (i.e., its width), it exhibits strong insulation due to the insertion of the non-conductive PMMA microribbon. Janus microribbons possess weak microscopic anisotropic conductivity. When used as building blocks and oriented, the resulting array film exhibits weak conductivity along the length of the Janus microribbons and strong insulation along the width direction perpendicular to its length, resulting in weak anisotropic conductivity. However, at high temperatures, the strong conductivity of VO2 after its phase transition leads to strong conductivity on the VO2 / PMMA microribbon side. For a single Janus microribbon, the conductivity along the length direction of the Janus microribbon is due to the strong conductivity on the VO2 / PMMA side. While exhibiting strong conductivity, the Janus microbelt possesses strong insulation along its width (perpendicular to its length) due to the insertion of non-conductive PMMA microbelts. This results in strong microscopic anisotropic conductivity of the Janus microbelt. Orienting these microbelts as building blocks yields an array film with strong conductivity along its length and strong insulation along its width (perpendicular to its length), resulting in strong anisotropic conductivity and thermotropic anisotropic conductivity. This novel thermotropic conductive film holds significant promise for future applications in the electronics industry, flexible electronics, energy storage, and sensing. Currently, no related literature reports have been found.

[0006] US Patent No. 1975504 discloses a technical solution for electrospinning, an effective method for preparing continuous micro / nanofibers with macroscopic lengths. This method was first proposed by Formals in 1934. Primarily used to prepare polymer nanofibers, this method involves using an electrostatic field to force a charged polymer solution or melt to be ejected from a nozzle and projected onto a receiving screen, thus achieving fiber drawing. The solvent then evaporates at room temperature, or the melt cools to room temperature and solidifies, yielding micro / nanofibers. These fibers accumulate to form a micro / nanofiber membrane. QZYu et al. prepared conductive polyaniline (PANI) nanofiber membranes using electrospinning technology (also known as electrospinning technique) [Mater. Sci. Eng. B, 2008, 150, 70-76]; Liu Tianxi et al. from Fudan University prepared anisotropic conductive membranes composed of nanofibers using uniaxial electrospinning technology [Nanoscale, 2015, 7, 1037-1046]; Dong Xiangting et al. constructed magneto-optically functionalized anisotropic conductive membranes using terbium complexes as luminescent materials, Fe3O4 nanocrystals as magnetic materials, and PANI as conductive materials, with Janus nanoribbons as building blocks [Adv. Funct. Mater. 2015, 25, 2436-2443]. Currently, there are no reports on constructing thermo-anisotropic conductive membranes using VO2 with thermally induced phase transition properties as conductive materials and Janus microribbons as building blocks.

[0007] When preparing micro- and nanomaterials using electrospinning technology, the type of raw materials, the molecular weight of the polymer template agent, the composition of the spinning solution, the spinning process parameters, and the structure of the spinneret all have a significant impact on the morphology and size of the final product. This invention uses a biaxial parallel spinning spinneret and employs electrospinning technology. Polymethyl methacrylate (PMMA) is mixed with solvents N,N-dimethylformamide (DMF) and chloroform (CHCl3) to prepare a spinning solution with a certain viscosity, referred to as spinning solution A. VO2(M) is added to the mixed solvent containing DMF and CHCl3, ultrasonically dispersed, and then PMMA is added to obtain another spinning solution with a certain viscosity, referred to as spinning solution B. Controlling the viscosity of the spinning solution is crucial. An aluminum rotating drum is used as the receiving device for Janus microbelts. Under optimal process conditions, a [PMMA] / / [VO2 / PMMA] Janus microbelt array film is obtained. This array film exhibits strong thermotropic anisotropic conductivity, i.e., a thermotropic anisotropic conductive film. Summary of the Invention

[0008] In the background technology, conductive polymer polyaniline (PANI) was used as the conductive material, and conductive functional nanofibers and anisotropic conductive films were prepared using uniaxial electrospinning technology. A magneto-optically functionalized anisotropic conductive Janus nanoribbon array film was prepared using a two-parallel spinneret and electrospinning technology. The raw materials, template agents, solvents, and final target products used differ from the method of this invention. This invention uses a two-axis parallel spinning spinneret and an aluminum rotary drum as the receiving device. [PMMA] / / [VO2 / PMMA] Janus microribbons were prepared using electrospinning technology. These Janus microribbons were then used as building blocks and also as conductive units to prepare a Janus microribbon array film with thermally induced anisotropic conductivity, adding a novel conductive functional material to the field of anisotropic conductive film materials.

[0009] This invention is achieved as follows: Polymethyl methacrylate (PMMA) is mixed with solvents N,N-dimethylformamide (DMF) and chloroform (CHCl3) to prepare a spinning solution with a certain viscosity, referred to as spinning solution A. VO2(M) is added to the mixed solvent containing DMF and CHCl3, ultrasonically dispersed, and then PMMA is added to obtain another spinning solution with a certain viscosity, referred to as spinning solution B. Controlling the viscosity of the spinning solution is crucial. An aluminum rotating drum is used as the receiving device for Janus microbelts. Under optimal process conditions, a thermotropic anisotropic conductive film of [PMMA] / / [VO2 / PMMA] Janus microbelt array is obtained. The steps are as follows:

[0010] (1) Preparation of VO2(M) by combining hydrothermal treatment and high-temperature calcination

[0011] 0.91 g V2O5 was dispersed in 400 mL of deionized water and magnetically stirred for 0.5 h. Then, 1.26 g of oxalic acid dihydrate C2H2O4·2H2O was added and stirring was continued for 0.5 h. The resulting yellow suspension was transferred to a stainless steel high-pressure reactor lined with polytetrafluoroethylene and kept at 200 °C for 48 h. The high-pressure reactor was then slowly cooled to room temperature. The resulting powder sample was washed three times each with deionized water and ethanol to remove unreacted impurities and dried in an oven at 80 °C for 6 h to obtain VO2(B). VO2(B) was then placed in a carbonization furnace and heated to 500 °C at a heating rate of 2 °C / min under a nitrogen atmosphere and held for 2 h. Finally, it was cooled to room temperature at a cooling rate of 5 °C / min to obtain VO2(M).

[0012] (2) Preparation of polymethyl methacrylate (PMMA) by bulk polymerization

[0013] Weigh 0.1g benzoyl peroxide (BPO) and 100g methyl methacrylate (MMA), add them to a 250mL three-necked flask equipped with a reflux device and stir well. Continuously stir the mixture magnetically at 110℃. When the viscosity of the solution is similar to that of glycerol, stop heating while continuing to stir and allow it to cool naturally to room temperature. Then pour the solution with the obtained viscosity into a test tube and let it stand for 3 days until the bubbles in the test tube completely disappear. After that, transfer the test tube to a 50℃ drying oven and place it for 48 hours. The liquid in the test tube hardens into a transparent solid. Finally, raise the temperature of the drying oven to 110℃ and keep it at that temperature for 3 hours to complete the polymerization reaction. Allow it to cool naturally to room temperature to obtain PMMA.

[0014] (3) Preparation of spinning solution

[0015] 0.50 g PMMA was added to a mixed solvent containing 2.00 g DMF and 8.00 g CHCl3, and the mixture was magnetically stirred for 24 h to obtain spinning solution A; 1.00 g VO2(M) was added to a mixed solvent containing 2.00 g DMF and 8.00 g CHCl3, and the mixture was ultrasonically dispersed for 0.5 h, then 0.50 g PMMA was added, and the mixture was magnetically stirred for 24 h to obtain spinning solution B;

[0016] (4) Thermotropic anisotropic conductive film of [PMMA] / / [VO2 / PMMA] Janus microbelt array was prepared by biaxial parallel electrospinning technology.

[0017] Two flattened #12 stainless steel needles were bent at 30° angles to make the two stainless steel needle tips closely parallel and fixed with copper wire. A 1mL plastic spray gun head was then attached, with the two stainless steel needle tips located in the middle of the plastic spray gun head, forming a biaxial parallel spinneret. Two 10mL syringes were installed on it, filled with spinning solution A and spinning solution B respectively. The biaxial parallel spinneret was connected to the positive terminal of a high-voltage power supply, and a +7kV DC voltage was applied. A grounded cylindrical aluminum drum was used as a collection device, placed 12cm away from the tip of the spray gun head. The drum rotation speed was 1000r / min. Throughout the spinning process, the ambient temperature was 20-24℃ and the relative humidity was 27%-34%. After the spinning solution was completely exhausted, a [PMMA] / / [VO2 / PMMA]Janus microbelt array thermotropic anisotropic conductive film was obtained.

[0018] The thermotropic anisotropic conductive film prepared in the above process is formed by oriented [PMMA] / / [VO2 / PMMA] Janus microbands in one direction, forming an array film. The average width of the Janus microbands is 7.11 ± 0.06 μm. When there is no heating (i.e., at room temperature), the conductivity of the thermotropic anisotropic conductive film along the length of the Janus microbands is 9.54 × 10⁻⁶. -8S, while the conductivity along the width direction of the Janus microband is 1.63 × 10⁻⁶. -9 The ratio of conductance in the two directions is 5.81 × 10⁻⁶. 1 The array film exhibits weak anisotropic conductivity; when heated to 80°C, the conductivity of the thermally induced anisotropic conductive film along the length of the Janus microband is 2.19 × 10⁻⁶. -5 S exhibits thermally induced conductivity, with a conductivity of 1.81 × 10⁻⁶ along the width of the Janus microband. -9 S remains insulating, and the ratio of its conductances in the two directions is 1.22 × 10⁻⁶. 4 The thermotropic anisotropic conductive film exhibits strong thermotropic anisotropic conductivity. That is, when not heated, the thermotropic anisotropic conductive film has weak anisotropic conductivity, but when heated, it has strong thermotropic anisotropic conductivity. Thus, high thermotropic anisotropic conductivity is achieved through heating. The constructed [PMMA] / / [VO2 / PMMA] Janus microbelt array film is a thermotropic anisotropic conductive film, thus achieving the purpose of the invention. Attached Figure Description

[0019] Figure 1 This is the XRD pattern of a thermally induced anisotropic conductive film of [PMMA] / / [VO2 / PMMA] Janus microbelt array;

[0020] Figure 2 This is a SEM image of a thermally induced anisotropic conductive film of [PMMA] / / [VO2 / PMMA] Janus microband array, which also serves as an appendix to the abstract.

[0021] Figure 3 This is a histogram of the width distribution of Janus microbands in a thermally induced anisotropic conductive film of [PMMA] / / [VO2 / PMMA] Janus microband array;

[0022] Figure 4 This is an EDS line analysis diagram of a single Janus microband in a thermally induced anisotropic conductive film of [PMMA] / / [VO2 / PMMA] Janus microband array;

[0023] Figure 5 This is the DSC curve of the [PMMA] / / [VO2 / PMMA] Janus microband array thermally induced anisotropic conductive film;

[0024] Figure 6 It is a ring-shaped curve showing the change in conductivity of the [PMMA] / / [VO2 / PMMA] Janus microband array thermally induced anisotropic conductive film along the length of the Janus microband as a function of temperature. Detailed Implementation

[0025] The vanadium pentoxide (V₂O₅), oxalic acid dihydrate (C₂H₂O₄·2H₂O), benzoyl peroxide (BPO), methyl methacrylate (MMA), anhydrous ethanol, nitrogen, N,N-dimethylformamide (DMF), and chloroform (CHCl₃) used in this invention are all commercially available analytical grade products; deionized water is prepared in the laboratory; and the glassware and equipment used are commonly used in laboratories.

[0026] Example: 0.91 g V₂O₅ was dispersed in 400 mL of deionized water and magnetically stirred for 0.5 h. Then, 1.26 g of oxalic acid dihydrate (C₂H₂O₄·2H₂O) was added and stirring continued for another 0.5 h. The resulting yellow suspension was transferred to a stainless steel high-pressure reactor lined with polytetrafluoroethylene and kept at 200 °C for 48 h. The reactor was then slowly cooled to room temperature. The resulting powder sample was washed three times each with deionized water and ethanol to remove unreacted impurities, and then dried in an oven at 80 °C for 6 h to obtain VO₂(B). VO₂(B) was then placed in a carbonization furnace and heated to 500 °C at a heating rate of 2 °C / min under a nitrogen atmosphere and held for 2 h. Finally, it was cooled to room temperature at a cooling rate of 5 °C / min. Obtain VO2(M); Weigh 0.1g benzoyl peroxide (BPO) and 100g methyl methacrylate (MMA), add them to a 250mL three-necked flask equipped with a reflux device and stir well. Continuously stir the mixture magnetically at 110℃ until the viscosity is similar to that of glycerol. Stop heating while continuing stirring and allow it to cool naturally to room temperature. Pour the resulting solution into a test tube and let it stand for 3 days until all bubbles disappear. Then, place the test tube in a 50℃ drying oven for 48 hours. The liquid in the test tube will harden into a transparent solid. Finally, raise the oven temperature to 110℃ and maintain it for 3 hours to complete the polymerization reaction. Allow it to cool naturally to room temperature to obtain PMMA; Add 0.50g... PMMA was added to a mixed solvent containing 2.00 g DMF and 8.00 g CHCl3, and the mixture was magnetically stirred for 24 h to obtain spinning solution A. 1.00 g VO2(M) was added to a mixed solvent containing 2.00 g DMF and 8.00 g CHCl3, and the mixture was ultrasonically dispersed for 0.5 h. Then, 0.50 g of [unspecified substance] was added. PMMA was magnetically stirred for 24 hours to obtain spinning solution B. Two 12# stainless steel needles with flattened tips were bent at 30° angles to make the two stainless steel needle tips closely parallel and fixed with copper wire. A 1mL plastic spray gun head was then attached, with the two stainless steel needle tips located in the middle of the plastic spray gun head to form a biaxial parallel spinneret. Two 10mL syringes were installed on it, filled with spinning solution A and spinning solution B respectively. The biaxial parallel spinneret was connected to the positive terminal of a high-voltage power supply, and a +7kV DC voltage was applied. A grounded cylindrical aluminum drum was used as a collection device, placed 12cm away from the tip of the spray gun head. The drum rotation speed was 1000r / min. Throughout the spinning process, the ambient temperature was 20-24℃ and the relative humidity was 27%-34%. After the spinning solution was completely exhausted, a [PMMA] / / [VO2 / PMMA]Janus microbelt array thermotropic anisotropic conductive film was obtained. The [PMMA] / / [VO2 / PMMA] Janus microband array thermally induced anisotropic conductive film contains monoclinic VO2(M), see [link to article]. Figure 1As shown; in the [PMMA] / / [VO2 / PMMA] Janus microband array thermally induced anisotropic conductive film, Janus microbands are oriented in one direction to form an array film, see... Figure 2 As shown; the average width of the Janus microbands in the [PMMA] / / [VO2 / PMMA] Janus microband array thermally induced anisotropic conductive film is 7.11±0.06μm, see Figure 3 As shown; in the [PMMA] / / [VO2 / PMMA] Janus microband array thermally induced anisotropic conductive film, the V element in a single Janus microband exists only on the left half of the Janus microband, which is consistent with the structure of the Janus microband. Figure 4 As shown; the [PMMA] / / [VO2 / PMMA] Janus microband array thermally induced anisotropic conductive film exhibits an endothermic phase transition peak at 67.89℃ during heating, consistent with the phase transition temperature of pure VO2. Upon cooling, it shows an exothermic phase transition peak at 59.35℃, indicating a temperature hysteresis phenomenon. (See...) Figure 5 As shown; the [PMMA] / / [VO2 / PMMA] Janus microband array thermotropically anisotropic conductive film exhibits abrupt changes in conductivity along the length of the Janus microbands near the phase transition temperature during heating. Subsequently, it shows a slight increase with rising temperature. When the temperature exceeds 80°C, the conductivity remains essentially constant, indicating that the strongest conductivity has been reached. Therefore, the thermotropic conductivity test temperature was set to 80°C. During cooling, the conductivity recovers to its initial level as the temperature decreases, and the conductivity at the beginning and end of the heating / cooling curves is consistent, indicating that the VO2 phase transition in the thermotropically anisotropic conductive film is completely reversible. See [link to relevant documentation]. Figure 6 As shown; when there is no heating, i.e., at room temperature, the conductivity of the thermally induced anisotropic conductive film along the length of the Janus microband is 9.54 × 10⁻⁶. -8 S, while the conductivity along the width direction of the Janus microband is 1.63 × 10⁻⁶. -9 The ratio of conductance in the two directions is 5.81 × 10⁻⁶. 1 The array film exhibits weak anisotropic conductivity; when heated to 80°C, the conductivity of the thermally induced anisotropic conductive film along the length of the Janus microband is 2.19 × 10⁻⁶. -5 S exhibits thermally induced conductivity, with a conductivity of 1.81 × 10⁻⁶ along the width of the Janus microband. -9 S remains insulating, and the ratio of its conductances in the two directions is 1.22 × 10⁻⁶. 4Thermotropic anisotropic conductive film has strong thermotropic anisotropic conductivity. That is, when not heated, the thermotropic anisotropic conductive film has weak anisotropic conductivity, but when heated, it has strong thermotropic anisotropic conductivity. Thus, high thermotropic anisotropic conductivity is achieved through heating, and a thermotropic anisotropic conductive film is obtained.

[0027] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A thermotropic anisotropic conductive film, characterized in that, An array film is formed by arranging [PMMA] / / [VO2 / PMMA] Janus microbands in one direction, with each Janus microband having an average width of 7.11±0.06μm. The prepared thermotropic anisotropic conductive film has strong thermotropic anisotropic conductivity.

2. A method for preparing a thermally induced anisotropic conductive film as described in claim 1, characterized in that, Electrospinning technology was employed, using a biaxial parallel spinning spinneret and a mixed solvent of N,N-dimethylformamide (DMF) and chloroform (CHCl3), to prepare a [PMMA] / / [VO2 / PMMA]Janus microbelt array thermally induced anisotropic conductive film. The steps were as follows: (1) Preparation of VO2(M) by combining hydrothermal treatment and high-temperature calcination 0.91 g V2O5 was dispersed in 400 mL of deionized water and magnetically stirred for 0.5 h. Then, 1.26 g of oxalic acid dihydrate C2H2O4·2H2O was added and stirring was continued for 0.5 h. The resulting yellow suspension was transferred to a stainless steel high-pressure reactor lined with polytetrafluoroethylene and kept at 200 °C for 48 h. The high-pressure reactor was then slowly cooled to room temperature. The resulting powder sample was washed three times each with deionized water and ethanol to remove unreacted impurities and dried in an oven at 80 °C for 6 h to obtain VO2(B). VO2(B) was then placed in a carbonization furnace and heated to 500 °C at a heating rate of 2 °C / min under a nitrogen atmosphere and held for 2 h. Finally, it was cooled to room temperature at a cooling rate of 5 °C / min to obtain VO2(M). (2) Preparation of polymethyl methacrylate (PMMA) by bulk polymerization Weigh 0.1g benzoyl peroxide (BPO) and 100g methyl methacrylate (MMA), add them to a 250mL three-necked flask equipped with a reflux device and stir well. Continuously stir the mixture magnetically at 110℃. When the viscosity of the solution is similar to that of glycerol, stop heating while continuing to stir and allow it to cool naturally to room temperature. Then pour the solution with the obtained viscosity into a test tube and let it stand for 3 days until the bubbles in the test tube completely disappear. After that, transfer the test tube to a 50℃ drying oven and place it for 48 hours. The liquid in the test tube hardens into a transparent solid. Finally, raise the temperature of the drying oven to 110℃ and keep it at that temperature for 3 hours to complete the polymerization reaction. Allow it to cool naturally to room temperature to obtain PMMA. (3) Preparation of spinning solution 0.50 g PMMA was added to a mixed solvent containing 2.00 g DMF and 8.00 g CHCl3, and the mixture was magnetically stirred for 24 h to obtain spinning solution A; 1.00 g VO2(M) was added to a mixed solvent containing 2.00 g DMF and 8.00 g CHCl3, and the mixture was ultrasonically dispersed for 0.5 h, then 0.50 g PMMA was added, and the mixture was magnetically stirred for 24 h to obtain spinning solution B; (4) Thermotropic anisotropic conductive film of [PMMA] / / [VO2 / PMMA] Janus microbelt array was prepared by biaxial parallel electrospinning technology. Two flattened #12 stainless steel needles are bent at 30° angles to ensure their tips are closely aligned and parallel, then secured with copper wire. A 1mL plastic spray gun head is then fitted over the needles, positioning the two stainless steel needle tips in the center of the spray gun head to form a parallel spinneret. Two 10mL syringes are mounted on the spinneret, filled with spinning solution A and spinning solution B respectively. The parallel spinneret is connected to the positive terminal of a high-voltage power supply, applying a +7kV DC voltage. A grounded cylindrical aluminum drum is used as the collection device, placed 12cm from the tip of the spray gun head, and rotated at 1000 rpm. Throughout the spinning process, the ambient temperature was 20-24℃ and the relative humidity was 27%-34%. After the spinning solution was completely exhausted, a thermotropic anisotropic conductive film of [PMMA] / / [VO2 / PMMA] Janus microbelt array was obtained. The array film was formed by oriented [PMMA] / / [VO2 / PMMA] Janus microbelts in one direction, with an average width of 7.11±0.06μm. When there was no heating (i.e., at room temperature), the conductivity of the thermotropic anisotropic conductive film along the length of the Janus microbelts was 9.54×10⁻⁶. -8 S, while the conductivity along the width direction of the Janus microband is 1.63 × 10⁻⁶. -9 The ratio of conductance in the two directions is 5.81 × 10⁻⁶. 1 The array film exhibits weak anisotropic conductivity; when heated to 80°C, the conductivity of the thermally induced anisotropic conductive film along the length of the Janus microband is 2.19 × 10⁻⁶. -5 S exhibits thermally induced conductivity, with a conductivity of 1.81 × 10⁻⁶ along the width of the Janus microband. -9 S remains insulating, and the ratio of its conductances in the two directions is 1.22 × 10⁻⁶. 4 The thermotropic anisotropic conductive film exhibits strong thermotropic anisotropic conductivity. That is, when not heated, the thermotropic anisotropic conductive film has weak anisotropic conductivity, but when heated, it has strong thermotropic anisotropic conductivity. Thus, high thermotropic anisotropic conductivity is achieved through heating. The constructed [PMMA] / / [VO2 / PMMA] Janus microbelt array thermotropic anisotropic conductive film has good thermotropic anisotropic conductivity characteristics.

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