Preparation method of multi-component parallel micro-nanofiber

Abstract

The application discloses a kind of preparation methods of multi-component parallel micro-nanofiber, comprising the following steps: step one, preparation core-sheath type multi-fluid spinning nozzle;Step two, prepare spinning solution;Step three, multi-component micro-nanofiber is prepared using multi-fluid spinning;Step four, remove the outer layer of fiber to prepare multi-component parallel micro-nanofiber, obtain multi-component parallel micro-nanofiber.The application prepares original fiber by "core-sheath type" multi-fluid electrospinning technology, removes the outer layer of fiber by appropriate post-processing method, obtains internal parallel fiber, successfully prepares a series of multi-component parallel micro-nanofiber by changing the composition of different fluids, improves the forming rate of multi-component parallel micro-nanofiber preparation, reduces the preparation difficulty, widens applicable spinning system, and multi-component parallel micro-nanofiber can realize the compounding of multiple materials and the integration of multifunction, and has wide application in catalysis, electromagnetic shielding, biological medicine and the like.

Description

Technical Field

[0001] This invention belongs to the field of micro and nanomaterial preparation technology, specifically relating to a method for preparing multi-component parallel micro and nanofibers. Background Technology

[0002] Electrospinning is an advanced manufacturing technology that uses a high-voltage electric field to stretch polymer solutions to form submicron to nanoscale fibers. The resulting fibers possess extremely high specific surface areas and have wide applications in catalysis, energy, and biology. However, with technological advancements, single-component, single-structure, and single-function fibers are increasingly unable to meet the demands of highly efficient and intensive material development. Therefore, multi-component, composite micro / nanofibers are attracting increasing attention. Among these, multi-component parallel micro / nanofibers possess one or more continuous long-range heterojunctions, which can retain the properties of individual components while enhancing material performance through the interaction of the heterojunction, thus arousing widespread research interest.

[0003] In terms of the development of preparation methods, thanks to the advantage of rapid fiber formation during electrospinning, the structure of the resulting fiber largely depends on the structure of the spinning spinneret. Therefore, by optimizing the spinneret configuration, the micro / nano structure of the fiber can be easily adjusted. The most representative technology in this regard is multifluid electrospinning (Journal of the American Chemical Society, 2007, 129, 764-765), which achieves the composite of multiple materials and the formation of multiple structures during fiber formation by simultaneously using multiple spinnerets or realizing the parallel flow of multiple fluids within a single spinneret.

[0004] Conventional methods for preparing multi-component parallel micro / nanofibers often involve directly constructing parallel needles. However, this method is prone to jet splitting due to electrostatic repulsion during multi-component spinning. Therefore, there is a need for a method that uses an indirect approach, employing an external fluid to protect the parallel internal fluids, preventing jet splitting and improving the forming rate of multi-component parallel micro / nanofibers. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for preparing multi-component parallel micro / nanofibers. This method prepares raw fibers using a "core-wrapped" multifluid electrospinning technique, removes the outer layer of the fibers through appropriate post-processing, and obtains internally parallel fibers. By changing the composition of different fluids, a series of multi-component parallel micro / nanofibers are successfully prepared, improving the forming rate of multi-component parallel micro / nanofiber preparation, reducing the preparation difficulty, and broadening the applicable spinning systems.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing multi-component parallel micro / nanofibers, characterized in that the method includes the following steps:

[0007] Step 1: Preparation of a core-shell multifluid spinning spinneret:

[0008] By assembling one external fluid needle and two or more internal fluid needles of the same model, a core-wrap multi-fluid spinning spinneret is obtained.

[0009] Step 2: Prepare the spinning solution:

[0010] The linear polymer a is dissolved in organic solvent a and stirred thoroughly until completely dissolved to obtain an external fluid solution A with a concentration of 10% to 25%.

[0011] Multiple linear polymers b i Dissolve each component separately in organic solvent B and stir thoroughly until completely dissolved to obtain various internal fluid solutions B with concentrations ranging from 10% to 20%. i ;

[0012] Step 3: Prepare multi-component micro / nanofibers using multifluid spinning technology:

[0013] Multifluid electrospinning is performed using the spinneret obtained in step one. The external fluid solution A obtained in step two is injected into the external fluid needle of the spinneret, and the various internal fluid solutions B obtained in step two are respectively introduced into multiple internal fluid needles. Then, multifluid spinning is performed by applying a high voltage electrostatic field between the receiving substrate and the spinneret, and multi-component micro-nano fibers are obtained on the receiving substrate.

[0014] Step 4: Remove the outer layer of the fiber to prepare multi-component parallel micro / nanofibers:

[0015] The outer layer of the multi-component micro / nanofibers obtained in step three is removed to obtain multi-component parallel micro / nanofibers.

[0016] The multi-fluid spinning nozzle described in this invention is an assembly of an external fluid needle and multiple internal fluid needles. Specifically, multiple internal fluid needles are assembled and placed inside an external fluid needle, resulting in a core-encased multi-fluid spinning nozzle with nested internal fluid needles within the external fluid needle. Through multi-fluid spinning, a high-voltage electrostatic field is applied between the receiving substrate and the spinning nozzle. Under the stretching effect of the electric field force, the external fluid solution A and multiple internal fluid solutions B overcome surface tension at the spinneret, forming fibers that gradually become finer. Multi-component micro / nanofibers are obtained on the receiving substrate. Finally, the outer layer of the multi-component micro / nanofibers is removed, resulting in multi-component parallel micro / nanofibers. The multi-component parallel micro / nanofibers obtained by this invention have clear heterogeneous interfaces, retaining the inherent properties of each component while exhibiting synergistic effects of the heterogeneous interfaces. This improves the forming rate of multi-component parallel micro / nanofibers, reduces the preparation difficulty, broadens the applicable spinning systems, and promotes the development of this multifunctional fiber.

[0017] The above-mentioned method for preparing multi-component parallel micro / nanofibers is characterized in that, in step one, the outer fluid needle has a specification of 10G-12G, the inner fluid needle has a specification of 20G-23G, and multiple inner fluid needles are arranged closely in a straight line or regular polygon. The outlet of the inner fluid needle is flush with the outer fluid needle and protrudes 0.1mm-1mm from the outer fluid needle, and is placed at the geometric center of the outer fluid needle. In this invention, by controlling the specifications of the outer and inner fluid needles, the inner fluid needle is nested within the outer fluid needle. The arrangement of multiple inner fluid needles is selected according to actual needs to obtain different types of multi-component parallel micro / nanofibers. By making the outlet of the inner fluid needle flush with the outer fluid needle and protruding from the outer fluid needle, and placing it at the geometric center of the outer fluid needle, the outer fluid has better encapsulation of the inner fluid, resulting in more stable spinning.

[0018] The above-mentioned method for preparing multi-component parallel micro / nanofibers is characterized in that, in step two, the linear polymer a is polyvinylpyrrolidone or polyvinyl butyral, and the organic solvent a is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, ethanol, and acetone; the linear polymer b... i The polymer and organic solvent b are polyacrylonitrile, polyvinyl alcohol, polyvinylidene fluoride-hexafluoropropylene copolymer, polyurethane, polystyrene, polyacrylonitrile-styrene copolymer, polymethyl methacrylate, or polycaprolactone. The organic solvent b is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, tetrahydrofuran, and acetone. This invention prepares multi-component parallel micro / nanofiber fibers of different systems by controlling the types of polymers and organic solvents, which can be selected according to actual needs.

[0019] The above-described method for preparing multi-component parallel micro / nanofibers is characterized in that, in step two, the external fluid solution A and the internal fluid solution B...i The process involves adding precursor compounds, including tetrabutyl titanate (a precursor of TiO2), bismuth chloride and vanadium acetylacetonate (precursors of BiVO4), and anhydrous copper acetate (a precursor of Cu2O). This invention addresses the functionalization requirements of multi-component parallel micro / nanofibers, such as their use as catalysts, lithium-sulfur battery motors, etc., by dissolving different precursor compounds into the internal fluid.

[0020] The above-described method for preparing multi-component parallel micro / nanofibers is characterized in that, in step three, the external fluid solution A and the internal fluid solution B... i Both solutions are injected via a syringe pump. The flow rate of the external fluid solution A is denoted as x, the flow rate of the internal fluid solution B as y, and the number of internal fluid needles as n. x, y, and n satisfy: n ≤ x / y ≤ 3 × n. This invention uses a syringe pump to inject and control the flow rates of the external and internal fluid solutions, making the spinning process more stable.

[0021] It should be noted that when there are two internal fluid needles, the external fluid solution A and the internal fluid solution B... i The flow rate ratio is 2–6:1, where the flow rate of the external fluid solution A is 1.0 mL / h–2.0 mL / h, and the flow rate of the internal fluid solution B is… i The flow rate is 0.15 mL / h to 1.0 mL / h; when there are three internal fluid needles, the external fluid solution A and the internal fluid solution B... i The flow rate ratio is 3–9:1, where the flow rate of the external fluid solution A is 1.0 mL / h–2.0 mL / h, and the flow rate of the internal fluid solution B is... i The flow rate is 0.11 mL / h to 0.66 mL / h; when there are four internal fluid needles, the external fluid solution A and the internal fluid solution B... i The flow rate ratio is 4–12:1, where the flow rate of the external fluid solution A is 1.2 mL / h–2.0 mL / h, and the flow rate of the internal fluid solution B is... i The flow rate is 0.10 mL / h to 0.3 mL / h.

[0022] The above-described method for preparing multi-component parallel micro / nanofibers is characterized in that, in step three, during multi-fluid spinning, the distance between the receiving substrate and the spinneret is 12cm–25cm, the operating voltage is 8kV–20kV, and the multi-fluid spinning time is 15min–45min. This invention ensures stable spinning by controlling the parameters of multi-fluid spinning, thereby guaranteeing the quality of the multi-component parallel micro / nanofibers.

[0023] The above-mentioned method for preparing multi-component parallel micro / nanofibers is characterized in that the removal in step four involves dissolving the outer layer of the fiber in ethanol or water. Specifically, when the external fluid solution A is composed of polyvinylpyrrolidone, the multi-component micro / nanofibers are immersed in deionized water, then sonicated for at least 20 minutes, repeated three times, and then dried. When the external fluid solution A is composed of polyvinyl butyral, the multi-component micro / nanofibers are immersed in anhydrous ethanol, then sonicated for at least 20 minutes, repeated three times, and then dried. This invention, by controlling the removal process, achieves complete removal of the fiber outer layer without affecting the multi-component parallel micro / nanofibers.

[0024] The above-described method for preparing multi-component parallel micro / nanofibers is characterized in that the removal in step four involves calcination to remove the outer layer of the fiber. Specifically, the multi-component micro / nanofibers are calcined in a muffle furnace and then naturally cooled. This invention, by controlling the removal process, achieves complete removal of the fiber outer layer without affecting the multi-component parallel micro / nanofibers.

[0025] The above-mentioned method for preparing multi-component parallel micro / nanofibers is characterized in that, in step four, the adjacent parallel fibers in the multi-component parallel micro / nanofibers have different compositions, the cross-sectional morphology of the multi-component parallel micro / nanofibers is a straight parallel structure or a regular polygonal parallel structure, and the width of the multi-component parallel micro / nanofibers is 500 nm to 3 μm.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. This invention addresses the problem of easy jet splitting when preparing multi-component parallel micro / nanofibers using electrospinning. It proposes to use a "core-wrapped" multifluid electrospinning technique, in which multiple inner fluids are wrapped by an outer fluid to stabilize the spinning process. Combined with a post-processing step to remove the outer protective layer, multi-component parallel micro / nanofibers are obtained.

[0028] 2. The heterostructure of the multi-component parallel micro / nanofiber obtained by this invention is clear, which can not only retain the inherent properties of each component, but also have the synergistic effect of the heterostructure. The method proposed in this invention is beneficial to improving the forming rate of multi-component parallel micro / nanofiber preparation, reducing the preparation difficulty, broadening the applicable spinning system, and promoting the development of this multifunctional fiber.

[0029] 3. The method for multi-component parallel micro / nanofiber disclosed in this invention involves an outer fluid encapsulating an inner fluid, resulting in a stable spinning process and a high fiber formation rate.

[0030] 4. This invention has a wide range of applications. In terms of the number of components, it can be used to prepare fibers with double parallel, triple parallel, and quadruple parallel connections. In terms of structural control, it can be used to prepare fibers with linear parallel, triangular parallel, and square parallel connections.

[0031] 5. The multi-component parallel micro / nanofibers of the present invention can realize the composite of various materials and the integration of multiple functions, and have clear long-range heterogeneous interfaces, which can be widely used in photocatalysis, electrocatalysis, electromagnetic shielding, biomedicine and other fields.

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0033] Figure 1 This is a photograph of the outlet of the core-wrap multifluid spinning spinneret when there are two internal fluid needles in Embodiment 1 of the present invention.

[0034] Figure 2 This is a SEM image of the PAN / PS bicomponent parallel micro / nanofibers prepared in Example 1 of this invention.

[0035] Figure 3 This is a photograph of the outlet of the core-wrap multifluid spinning spinneret when there are three internal fluid needles arranged in a straight line, as shown in Embodiment 2 of the present invention.

[0036] Figure 4 This is a SEM image of the PAN / PS / PVDF-HFP three-component parallel micro / nanofibers prepared in Example 2 of the present invention.

[0037] Figure 5 This is a schematic diagram of the outlet of the core-wrap multifluid spinning spinneret when there are three internal fluid needles arranged in an equilateral triangle in Embodiment 5 of the present invention. Detailed Implementation

[0038] Example 1

[0039] This embodiment includes the following steps:

[0040] Step 1: Preparation of a core-spun two-fluid spinning spinneret:

[0041] Two 20G internal fluid spinnerets are bonded together in a straight line using solder. They are then placed at the geometric center of an 11G external fluid spinneret, with the outlet of the internal fluid spinneret flush with and protruding 0.1mm from the external fluid spinneret. This is followed by fixing to obtain a core-wrap dual-fluid spinning spinneret. (See...) Figure 1 ;

[0042] Step 2: Prepare the spinning solution:

[0043] Polyvinylpyrrolidone was dissolved in N,N-dimethylacetamide and stirred thoroughly until completely dissolved to obtain external fluid solution A with a concentration of 20%; polyacrylonitrile (PAN) was dissolved in N,N-dimethylformamide and stirred thoroughly in a 60°C water bath until completely dissolved to obtain internal fluid solution B1 with a concentration of 15%; polystyrene (PS) was dissolved in N,N-dimethylformamide and stirred thoroughly until completely dissolved to obtain internal fluid solution B2 with a concentration of 25%.

[0044] Step 3: Prepare multi-component micro / nanofibers using multifluid spinning:

[0045] Multifluid electrospinning was performed using the spinneret obtained in step one. The external fluid solution A obtained in step two was injected into the external fluid needle of the spinneret, and the internal fluid solutions B1 and B2 were injected into the two internal fluid needles of the spinneret, respectively. The flow rate of the external fluid solution A was 1.2 mL / h, and the flow rates of the internal fluid solutions B1 and B2 were both 0.2 mL / h, with a flow rate ratio of 6:1. Then, multifluid spinning was performed by applying a high-voltage electrostatic field between the receiving substrate and the spinneret. The spinning working distance (i.e., the distance between the receiving substrate and the spinneret) was 15 cm, the working voltage was 10 kV, and the time was 15 min. Multi-component micro and nanofibers were obtained on the receiving substrate.

[0046] Step 4: Remove the outer layer of the fiber to prepare bicomponent parallel micro / nanofibers:

[0047] The multi-component micro / nanofibers obtained in step 3 were immersed in 200 mL of deionized water and sonicated for 20 min. After being removed, the deionized water was replaced. This process was repeated three times and then dried to obtain PAN / PS bicomponent parallel micro / nanofibers.

[0048] Figure 2 The image shows a SEM image of the PAN / PS bicomponent parallel micro / nanofibers prepared in this embodiment. Figure 2 As can be seen from the above, the PAN / PS bicomponent parallel micro / nanofibers prepared in this embodiment have a distinct double parallel fiber structure.

[0049] The width of the PAN / PS bicomponent parallel micro / nanofibers prepared in this embodiment was found to be 3 μm.

[0050] Example 2

[0051] This embodiment includes the following steps:

[0052] Step 1: Preparation of a core-shell three-fluid spinning spinneret:

[0053] Three 22G internal fluid needles were bonded together in a straight line using solder. They were then placed at the geometric center of a 10G external fluid needle, with the outlet of the internal fluid needle flush with and protruding 0.5mm from the external fluid needle. This resulted in a core-wrap three-fluid spinning spinneret. (See...) Figure 3 ;

[0054] Step 2: Prepare the spinning solution:

[0055] Polyvinyl butyral was dissolved in N,N-dimethylacetamide and stirred thoroughly until completely dissolved to obtain external fluid solution A with a concentration of 10%. Polyacrylonitrile (PAN) was dissolved in N,N-dimethylformamide and stirred thoroughly in a 60°C water bath until completely dissolved to obtain internal fluid solution B1 with a concentration of 15%. Polystyrene (PS) was dissolved in N,N-dimethylformamide and stirred thoroughly until completely dissolved to obtain internal fluid solution B2 with a concentration of 25%. Polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) was dissolved in a solvent of acetone and N,N-dimethylacetamide in a mass ratio of 7:3 and stirred thoroughly until completely dissolved to obtain internal fluid solution B3 with a concentration of 15%.

[0056] Step 3: Prepare multi-component micro / nanofibers using multifluid spinning:

[0057] Multifluid electrospinning was performed using the spinneret obtained in step one. The external fluid solution A obtained in step two was injected into the external fluid needle of the spinneret, and the internal fluid solutions B1, B2, and B3 were injected into the three internal fluid needles of the spinneret, with B2 located between B1 and B3. The flow rate of the external fluid solution A was 1.8 mL / h, and the flow rates of the internal fluid solutions B1, B2, and B3 were all 0.2 mL / h, with a flow rate ratio of 9:1. Multifluid spinning was then performed by applying a high-voltage electrostatic field between the receiving substrate and the spinneret. The spinning working distance (i.e., the distance between the receiving substrate and the spinneret) was 15 cm, the working voltage was 12 kV, and the time was 15 min, resulting in multi-component micro / nanofibers on the receiving substrate.

[0058] Step 4: Remove the outer layer of the fiber to prepare three-component parallel micro / nanofibers:

[0059] The multi-component micro / nanofibers obtained in step 3 were immersed in 200 mL of anhydrous ethanol and sonicated for 20 min. After removal, the anhydrous ethanol was replaced, and the process was repeated three times before drying to obtain PAN / PS / PVDF-HFP three-component parallel micro / nanofibers in a straight line.

[0060] Figure 4 This is a SEM image of the PAN / PS / PVDF-HFP three-component parallel micro / nanofibers prepared in this embodiment. Figure 4As can be seen from the above, the PAN / PS / PVDF-HFP three-component parallel micro / nanofibers prepared in this embodiment have a distinct three-parallel fiber structure.

[0061] The width of the PAN / PS / PVDF-HFP three-component parallel micro / nanofibers prepared in this embodiment was found to be 2.7 μm.

[0062] Example 3

[0063] This embodiment includes the following steps:

[0064] Step 1: Preparation of a core-spun two-fluid spinning spinneret:

[0065] Two 20G internal fluid needles are bonded together in a straight line using solder. Then, they are placed at the geometric center of a 12G external fluid needle, with the outlet of the internal fluid needle flush with and protruding 0.3mm from the external fluid needle. After fixing, a core-wrap dual-fluid spinning spinneret is obtained.

[0066] Step 2: Prepare the spinning solution:

[0067] Polyvinylpyrrolidone was dissolved in N,N-dimethylacetamide and stirred thoroughly until completely dissolved to obtain external fluid solution A with a concentration of 20%. 0.1 mmol of anhydrous copper acetate was dissolved in N,N-dimethylformamide, followed by the addition of polyacrylonitrile (PAN), and stirred thoroughly in a 60°C water bath until completely dissolved to obtain internal fluid solution B1 with a polymer concentration of 15%. Polystyrene (PS) was dissolved in N,N-dimethylformamide and stirred thoroughly until completely dissolved, followed by the addition of 0.1 mmol of tetrabutyl titanate and 0.1 mmol of acetylacetone, and stirred until the solution was homogeneous to obtain internal fluid solution B2 with a polymer concentration of 25%.

[0068] Step 3: Prepare multi-component micro / nanofibers using multifluid spinning:

[0069] Multifluid electrospinning was performed using the spinneret obtained in step one. The external fluid solution A obtained in step two was injected into the external fluid needle of the spinneret, and the internal fluid solutions B1 and B2 were injected into the two internal fluid needles of the spinneret, respectively. The flow rate of the external fluid solution A was 2.0 mL / h, and the flow rates of the internal fluid solutions B1 and B2 were 1.0 mL / h, with a flow rate ratio of 2:1. Then, multifluid spinning was performed by applying a high-voltage electrostatic field between the receiving substrate and the spinneret. The spinning working distance (i.e., the distance between the receiving substrate and the spinneret) was 25 cm, the working voltage was 20 kV, and the time was 15 min. Multi-component micro and nanofibers were obtained on the receiving substrate.

[0070] Step 4: Remove the outer layer of the fiber to prepare bicomponent parallel micro / nanofibers:

[0071] The bicomponent micro / nanofibers obtained in step three were placed in a muffle furnace and heated from room temperature to 400°C at a rate of 2°C / min, held for 2 hours, and then allowed to cool naturally to room temperature. Subsequently, they were placed in a tube furnace and calcined under a 10% Ar / H2 atmosphere, heated to 400°C at a rate of 2°C / min, held for 2 hours, reducing CuO to photocatalytically active Cu2O. Finally, the mixture was allowed to cool naturally to room temperature to obtain Cu2O / TiO2 bicomponent parallel micro / nanofibers.

[0072] In this embodiment, organic solvent a may also be one or more of N,N-dimethylformamide, N,N-dimethylacetamide, ethanol, and acetone, and organic solvent b may also be one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, tetrahydrofuran, and acetone, and linear polymer b. i It can also be polyvinyl alcohol, polyvinylidene fluoride-hexafluoropropylene copolymer, polyurethane, polyacrylonitrile-styrene copolymer, polymethyl methacrylate or polycaprolactone.

[0073] The Cu2O / TiO2 bicomponent parallel micro / nanofibers prepared in this embodiment were found to have a width of 500 nm. When applied to the photocatalytic reduction of CO2, they were able to selectively produce methanol with a selectivity greater than 80%.

[0074] Example 4

[0075] This embodiment includes the following steps:

[0076] Step 1: Preparation of a core-shell three-fluid spinning spinneret:

[0077] Three 23G internal fluid needles are bonded together in a straight line using solder. Then, they are placed at the geometric center of a 10G external fluid needle, with the outlet of the internal fluid needle flush with and protruding 0.5mm from the external fluid needle. After fixing, a core-wrap three-fluid spinning spinneret is obtained.

[0078] Step 2: Prepare the spinning solution:

[0079] Polyvinylpyrrolidone was dissolved in N,N-dimethylacetamide and stirred thoroughly until completely dissolved to obtain external fluid solution A with a concentration of 20%. 0.1 mmol of bismuth chloride and 0.1 mmol of acetylacetonate vanadyl oxyacetate were dissolved in N,N-dimethylformamide, followed by the addition of polystyrene, and stirred thoroughly until completely dissolved to obtain internal fluid solution B1 with a polymer concentration of 25%. Polyacrylonitrile (PAN) was dissolved in N,N-dimethylformamide to prepare a 15% solution, resulting in internal fluid solution B2. Polystyrene was dissolved in N,N-dimethylformamide and stirred thoroughly until completely dissolved, followed by the addition of 0.1 mmol of tetrabutyl titanate and 0.1 mmol of acetylacetonate, and stirred continuously until the solution was homogeneous to obtain internal fluid solution B3 with a polymer concentration of 25%.

[0080] Step 3: Prepare multi-component micro / nanofibers using multifluid spinning:

[0081] Multifluid electrospinning was performed using the spinneret obtained in step one. The external fluid solution A obtained in step two was injected into the external fluid needle of the spinneret, and the internal fluid solutions B1, B2, and B3 were injected into the three internal fluid needles of the spinneret, with B2 located between B1 and B3. The flow rate of the external fluid solution A was 2.0 mL / h, and the flow rates of the internal fluid solutions B1, B2, and B3 were all 0.66 mL / h, with a flow rate ratio of 3:1. Multifluid spinning was then performed by applying a high-voltage electrostatic field between the receiving substrate and the spinneret. The spinning working distance (i.e., the distance between the receiving substrate and the spinneret) was 15 cm, the working voltage was 12 kV, and the time was 20 min, resulting in the formation of multi-component micro / nanofibers on the receiving substrate.

[0082] Step 4: Remove the outer layer of the fiber to prepare multi-component parallel micro / nanofibers:

[0083] The multi-component micro / nanofibers obtained in step three were immersed in 200 mL of anhydrous ethanol and sonicated for 20 min. After removal, the ethanol was replaced with fresh anhydrous ethanol. This process was repeated three times and then dried. The fibers were then placed in a muffle furnace and pre-oxidized at 280 °C from room temperature for 2 h. Finally, the fibers were placed in a tube furnace and calcined in an Ar atmosphere at 2 °C / min to 700 °C for 2 h. This process yielded BiVO4 / C / TiO2 three-component parallel micro / nanofibers in a straight line.

[0084] Testing revealed that the width of the BiVO4 / C / TiO2 three-component parallel micro / nanofibers prepared in this embodiment was 1 μm. When applied to the photocatalytic reduction of CO2, they were able to selectively produce CH4 with a selectivity greater than 85%.

[0085] Example 5

[0086] This embodiment includes the following steps:

[0087] Step 1: Preparation of a core-shell three-fluid spinning spinneret:

[0088] Three 22G internal fluid needles were bonded together in an equilateral triangle using solder. They were then placed at the geometric center of a 10G external fluid needle, with the outlet of the internal fluid needle flush with and protruding 1mm from the external fluid needle. This resulted in a core-wrap three-fluid spinning spinneret. (See...) Figure 5 ;

[0089] Step 2: Prepare the spinning solution:

[0090] Polyvinyl butyral was dissolved in N,N-dimethylacetamide and stirred thoroughly until completely dissolved to obtain external fluid solution A with a concentration of 10%. Polyacrylonitrile (PAN) was dissolved in N,N-dimethylformamide and stirred thoroughly in a 60°C water bath until completely dissolved to obtain internal fluid solution B1 with a concentration of 15%. Polystyrene (PS) was dissolved in N,N-dimethylformamide and stirred thoroughly until completely dissolved to obtain internal fluid solution B2 with a concentration of 25%. Polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) was dissolved in a solvent of acetone and N,N-dimethylacetamide in a mass ratio of 7:3 and stirred thoroughly until completely dissolved to obtain internal fluid solution B3 with a concentration of 15%.

[0091] Step 3: Prepare multi-component micro / nanofibers using multifluid spinning:

[0092] Multifluid electrospinning was performed using the spinneret obtained in step one. The external fluid solution A obtained in step two was injected into the external fluid needle of the spinneret, and the internal fluid solutions B1, B2, and B3 were injected into the three internal fluid needles of the spinneret, respectively. The flow rate of the external fluid solution A was 1.0 mL / h, and the flow rates of the internal fluid solutions B1, B2, and B3 were all 0.11 mL / h, with a flow rate ratio of 9:1. Then, multifluid spinning was performed by applying a high-voltage electrostatic field between the receiving substrate and the spinneret. The spinning working distance (i.e., the distance between the receiving substrate and the spinneret) was 12 cm, the working voltage was 8 kV, and the time was 45 min, resulting in the formation of multi-component micro / nanofibers on the receiving substrate.

[0093] Step 4: Remove the outer layer of the fiber to prepare three-component equilateral triangular parallel micro / nanofibers:

[0094] The multi-component micro / nanofibers obtained in step 3 were immersed in 200 mL of anhydrous ethanol and sonicated for 20 min. After removal, the ethanol was replaced with fresh anhydrous ethanol. This process was repeated three times and then dried to obtain PAN / PS / PVDF-HFP three-component equilateral triangular parallel micro / nanofibers.

[0095] The width of the PAN / PS / PVDF-HFP three-component parallel micro / nanofibers prepared in this embodiment was found to be 1.8 μm.

[0096] Example 6

[0097] This embodiment includes the following steps:

[0098] Step 1: Preparation of a core-shell four-fluid spinning spinneret:

[0099] Four 23G internal fluid needles are bonded together in a straight line using solder. Then, they are placed at the geometric center of a 10G external fluid needle, with the outlet of the internal fluid needle flush with and protruding 0.5mm from the external fluid needle. After fixing, a core-wrap four-fluid spinning spinneret is obtained.

[0100] Step 2: Prepare the spinning solution:

[0101] Polyvinylpyrrolidone was dissolved in N,N-dimethylacetamide and stirred thoroughly until completely dissolved to obtain external fluid solution A with a concentration of 20%. Polyacrylonitrile (PAN) was dissolved in N,N-dimethylformamide and stirred thoroughly in a 60°C water bath until completely dissolved to obtain internal fluid solution B1 with a concentration of 15%. Polystyrene (PS) was dissolved in N,N-dimethylformamide and stirred thoroughly until completely dissolved to obtain internal fluid solution B2 with a concentration of 25%. Polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) was dissolved in a solvent of acetone and N,N-dimethylacetamide in a mass ratio of 7:3 and stirred thoroughly until completely dissolved to obtain internal fluid solution B3 with a concentration of 15%. Polyurethane (PU) was dissolved in a solvent of N,N-dimethylformamide and tetrahydrofuran in a mass ratio of 1:1 and stirred thoroughly until completely dissolved to obtain internal fluid B4 with a concentration of 10%.

[0102] Step 3: Prepare multi-component micro / nanofibers using multifluid spinning:

[0103] Multifluid electrospinning was performed using the spinneret obtained in step one. The external fluid solution A obtained in step two was injected into the external fluid needle of the spinneret, and the internal fluid solutions B1, B2, B3, and B4 were injected into the four internal fluid needles of the spinneret, respectively. The flow rate of the external fluid solution A was 2.0 mL / h, and the flow rates of the internal fluid solutions B1, B2, B3, and B4 were all 0.3 mL / h, with a flow rate ratio of approximately 7:1. Then, multifluid spinning was performed by applying a high-voltage electrostatic field between the receiving substrate and the spinneret. The spinning working distance (i.e., the distance between the receiving substrate and the spinneret) was 12 cm, the working voltage was 15 kV, and the time was 18 min, resulting in the formation of multi-component micro / nanofibers on the receiving substrate.

[0104] Step 4: Remove the outer layer of the fiber to prepare bicomponent parallel micro / nanofibers:

[0105] The multi-component micro / nanofibers obtained in step 3 were immersed in 200 mL of deionized water and sonicated for 20 min. After being removed, the deionized water was replaced. This process was repeated three times and then dried to obtain PAN / PS / PVDF / PU bicomponent parallel micro / nanofibers.

[0106] The width of the parallel micro / nanofibers (PAN / PS / PVDF / PU) prepared in this embodiment was found to be 3 μm.

[0107] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing multi-component parallel micro / nanofibers, characterized in that, The method includes the following steps: Step 1: Preparation of a core-shell multifluid spinning spinneret: Assemble one external fluid needle and two or more internal fluid needles of the same model, with the outlet of the internal fluid needle flush with the external fluid needle and protruding 0.1mm~1mm from the external fluid needle, to obtain a core-wrap multi-fluid spinning spinneret. Step 2: Prepare the spinning solution: Linear polymer a is dissolved in organic solvent a and stirred thoroughly until completely dissolved to obtain an external fluid solution A with a concentration of 10%~25%; A plurality of linear polymers b i are dissolved in an organic solvent b with sufficient stirring until completely dissolved, and a plurality of internal fluid solutions B having a concentration of 10% to 20% are obtained i ; Step 3: Prepare multi-component micro / nanofibers using multifluid spinning technology: Multifluid electrospinning is performed using the spinneret obtained in step one. The external fluid solution A obtained in step two is injected into the external fluid needle of the spinneret, and multiple internal fluid solutions B obtained in step two are respectively introduced into multiple internal fluid needles. Then, multifluid spinning is performed by applying a high-voltage electrostatic field between the receiving substrate and the spinneret, resulting in multi-component micro / nanofibers on the receiving substrate; the external fluid solution A and the internal fluid solution B... i All solutions are injected via a syringe pump. The flow rate of the external fluid solution A is denoted as x, the flow rate of the internal fluid solution B is denoted as y, and the number of internal fluid needles is denoted as n. x, y, and n satisfy: n≤x / y≤3×n. The external fluid solution A is composed of polyvinylpyrrolidone or polyvinyl butyral. Step 4: Remove the outer layer of the fiber to prepare multi-component parallel micro / nanofibers: The outer layer of the multi-component micro / nanofibers obtained in step three is removed to obtain multi-component parallel micro / nanofibers; the removal is carried out by dissolving the outer layer of the fibers in ethanol or water.

2. The method for preparing multi-component parallel micro / nanofibers according to claim 1, characterized in that, The external fluid needle in step one has a specification of 10G~12G, and the internal fluid needle has a specification of 20G~23G. Multiple internal fluid needles are arranged closely in a straight line or regular polygon and placed at the geometric center of the external fluid needle.

3. The method for preparing multi-component parallel micro / nanofibers according to claim 1, characterized in that, In step two, the linear polymer a is polyvinylpyrrolidone or polyvinyl butyral, and the organic solvent a is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, ethanol, and acetone; the linear polymer b i The solvent b is polyacrylonitrile, polyvinyl alcohol, polyvinylidene fluoride-hexafluoropropylene copolymer, polyurethane, polystyrene, polyacrylonitrile-styrene copolymer, polymethyl methacrylate or polycaprolactone, and the organic solvent b is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, tetrahydrofuran and acetone.

4. The method for preparing multi-component parallel micro / nanofibers according to claim 1, characterized in that, The external fluid solution A and the internal fluid solution B mentioned in step two i The mixture contains precursor compounds, including tetrabutyl titanate as a precursor of TiO2, bismuth chloride and vanadium acetylacetonate as precursors of BiVO4, and anhydrous copper acetate as a precursor of Cu2O.

5. The method for preparing multi-component parallel micro / nanofibers according to claim 1, characterized in that, In the multi-fluid spinning process described in step three, the distance between the receiving substrate and the spinneret is 12cm~25cm, the working voltage is 8kV~20kV, and the multi-fluid spinning time is 15min~45min.

6. The method for preparing multi-component parallel micro / nanofibers according to claim 1, characterized in that, The removal described in step four involves dissolving the outer layer of the fiber in ethanol or water. Specifically, when the component of the external fluid solution A is polyvinylpyrrolidone, the multi-component micro / nanofibers are immersed in deionized water, then sonicated for more than 20 minutes, repeated three times, and then dried. When the component of the external fluid solution A is polyvinyl butyral, the multi-component micro / nanofibers are immersed in anhydrous ethanol, then sonicated for more than 20 minutes, repeated three times, and then dried.

7. The method for preparing multi-component parallel micro / nanofibers according to claim 1, characterized in that, The removal mentioned in step four is the removal of the outer layer of the fiber by calcination. The specific process is as follows: the multi-component micro-nano fibers are placed in a muffle furnace for calcination and then naturally cooled.

8. The method for preparing multi-component parallel micro / nanofibers according to claim 1, characterized in that, In step four, the adjacent parallel fibers in the multi-component parallel micro / nanofiber have different compositions. The cross-sectional morphology of the multi-component parallel micro / nanofiber is a straight parallel structure or a regular polygonal parallel structure. The width of the multi-component parallel micro / nanofiber is 500 nm to 3 μm.

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