Preparation method of multi-component parallel micro-nano fiber

Abstract

The invention discloses a preparation method of multi-component parallel micro-nano fibers. The preparation method comprises the following steps: step 1, preparing a core-spun multi-fluid spinning nozzle; 2, preparing a spinning solution; step 3, preparing multi-component micro-nano fibers by adopting multi-fluid spinning; and 4, removing the outer layer of the fiber to prepare the multi-component parallel micro-nano fiber, so as to obtain the multi-component parallel micro-nano fiber. According to the preparation method, original fibers are prepared through a core-spun multi-fluid electrostatic spinning technology, the outer layers of the fibers are removed through a proper post-treatment mode to obtain the fibers with parallel connection inside, a series of multi-component parallel connection micro-nanofibers are successfully prepared by changing the components of different fluids, the forming rate of preparation of the multi-component parallel connection micro-nanofibers is increased, and the multi-component parallel connection micro-nanofibers are obtained. The preparation method is simple, the preparation difficulty is reduced, an applicable spinning system is widened, the multi-component parallel micro-nano fiber can realize compounding of various materials and integration of multiple functions, and the multi-component parallel micro-nano fiber has wide application in the aspects of catalysis, electromagnetic shielding, biological medicine and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of micro-nano materials, and specifically relates to a method for preparing multi-component parallel micro-nano fibers. Background Art

[0002] Electrospinning technology is an advanced manufacturing technology that uses a high-voltage electric field to stretch a polymer solution to form submicron to nanometer-scale fibers. The prepared fibers have an extremely high specific surface area and are widely used in catalysis, energy, biology, etc. However, with the development of technology, single-component, single-structure, and single-function fibers have gradually become unable to meet the needs of efficient and intensive material development. Therefore, multi-component, composite-structure micro-nano fibers have received more and more attention. Among them, multi-component parallel micro-nano fibers have one or more continuous long-range heterogeneous interfaces, which can not only retain the properties of a single component, but also improve the material performance under the action of the heterogeneous interface, which has aroused 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 will largely depend on the structure of the spinning spinneret, so by optimizing the configuration of the spinneret, the micro-nano structure of the fiber can be easily adjusted. In this regard, the most representative is the multi-fluid electrospinning technology (Journal of the American Chemical Society, 2007, 129, 764-765), which uses multiple spinnerets at the same time, or realizes the parallel flow of multiple fluids inside a spinneret, thereby realizing the composite of multiple materials and the formation of multiple structures during the fiber formation process.

[0004] The conventional preparation method of multi-component parallel micro-nano fibers often adopts the method of directly constructing parallel needles. When operating multi-component spinning, jet splitting due to electrostatic repulsion is prone to occur. Therefore, it is necessary to provide a preparation method of multi-component parallel micro-nano fibers that adopts an indirect method to use an external fluid to protect the parallel internal fluid, prevent the occurrence of jet splitting, and improve the molding rate of multi-component parallel micro-nano fibers. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing multi-component parallel micro-nano fibers in view of the deficiencies of the above-mentioned prior art. The method prepares the original fiber by "core-wrapped" multi-fluid electrospinning technology, removes the outer layer of the fiber by appropriate post-treatment, obtains the internal parallel fiber, and successfully prepares a series of multi-component parallel micro-nano fibers by changing the composition of different fluids, thereby improving the forming rate of the preparation of multi-component parallel micro-nano fibers, reducing the difficulty of preparation, and broadening the applicable spinning system.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing multi-component parallel micro-nano fibers, characterized in that the method comprises the following steps:

[0007] Step 1: Prepare a core-wrapped multi-fluid spinning spinneret:

[0008] Assembling an external fluid needle and two or more internal fluid needles of matching models to obtain a core-wrapped multi-fluid spinning spinneret;

[0009] Step 2: Prepare spinning solution:

[0010] Dissolve the linear polymer a in the organic solvent a and stir thoroughly until it is completely dissolved to obtain an external fluid solution A with a concentration of 10% to 25%;

[0011] Various linear polymers i Dissolve them in organic solvent B and stir them thoroughly until they are completely dissolved to obtain various internal fluid solutions B with concentrations of 10% to 20%. i ;

[0012] Step 3: Prepare multi-component micro-nano fibers using multi-fluid spinning technology:

[0013] Using the spinneret obtained in step 1 to perform multi-fluid electrospinning, injecting the external fluid solution A obtained in step 2 into the external fluid needle of the spinneret, respectively passing the multiple internal fluid solutions B obtained in step 2 into multiple internal fluid needles, and then applying a high-voltage electrostatic field between the receiving substrate and the spinneret to perform multi-fluid spinning, thereby obtaining multi-component micro-nano fibers on the receiving substrate;

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

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

[0016] The multi-fluid spinning nozzle described in the present invention is to assemble an external fluid needle and multiple internal fluid needles, that is, multiple internal fluid needles are assembled and put into the external fluid needle to obtain a core-wrapped multi-fluid spinning nozzle in which the internal fluid needle is nested in 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 action of the electric field force, the external fluid solution A and the multiple internal fluid solutions B overcome the surface tension at the spinneret and are stretched to form fibers and gradually refined to obtain multi-component micro-nano fibers on the receiving substrate. Finally, the outer layer of the multi-component micro-nano fibers is removed to obtain multi-component parallel micro-nano fibers. The multi-component parallel micro-nano fibers obtained by the present invention have clear heterogeneous interfaces, can retain the inherent properties of each component, and have the synergistic effect of the heterogeneous interface, which is beneficial to improve the forming rate of the preparation of multi-component parallel micro-nano fibers, reduce the difficulty of preparation, broaden the applicable spinning system, and promote the development of such multifunctional fibers.

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

[0018] The above-mentioned method for preparing multi-component parallel micro-nano fibers is characterized in that the linear polymer a in step 2 is polyvinyl pyrrolidone or polyvinyl butyral, the organic solvent a is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, ethanol and acetone; the linear polymer b i The organic 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. The present invention controls the types of polymers and organic solvents to prepare multi-component parallel micro-nano fibers of different systems, and selects them according to actual needs.

[0019] The above-mentioned method for preparing multi-component parallel micro-nano fibers is characterized in that the external fluid solution A and the internal fluid solution B in step 2i A precursor compound is added, wherein the precursor compound includes TiO 2 The precursor of tetrabutyl titanate, BiVO 4 The precursors of bismuth chloride and vanadyl acetylacetonate, Cu 2 The precursor anhydrous copper acetate of O. According to the functional requirements of the target multi-component parallel micro-nano fibers, such as being used as a catalyst, a lithium-sulfur battery motor, etc., different precursor compounds are dissolved into the inner fluid.

[0020] The above-mentioned method for preparing multi-component parallel micro-nano fibers is characterized in that the external fluid solution A and the internal fluid solution B in step 3 i Both are injected by a syringe pump, the flow rate of the external fluid solution A is recorded as x, the flow rate of the internal fluid solution B is recorded as y, the number of internal fluid needles is recorded as n, and x, y and n satisfy: n≤x / y≤3×n. The present invention uses a syringe pump to inject and control the flow rate of the external fluid solution and the internal fluid solution, so that the spinning process is more stable.

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

[0022] The above-mentioned method for preparing multi-component parallel micro-nano fibers is characterized in that, in the multi-fluid spinning in step 3, the distance between the receiving substrate and the spinneret is 12 cm to 25 cm, the working voltage is 8 kV to 20 kV, and the multi-fluid spinning time is 15 min to 45 min. The present invention ensures the stable spinning by controlling the parameters of the multi-fluid spinning, thereby ensuring the quality of the multi-component parallel micro-nano fibers.

[0023] The above-mentioned method for preparing a multi-component parallel micro-nano fiber is characterized in that the removal described in step 4 is to remove the outer layer of the fiber by dissolving in ethanol or water, and the specific process is: when the component of the external fluid solution A is polyvinyl pyrrolidone, the multi-component micro-nano fiber is immersed in deionized water, and then ultrasonicated 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-nano fiber is immersed in anhydrous ethanol, and then ultrasonicated for more than 20 minutes, repeated three times and then dried. The present invention achieves complete removal of the outer layer of the fiber without affecting the multi-component parallel micro-nano fiber by controlling the removal process.

[0024] The above-mentioned method for preparing multi-component parallel micro-nano fibers is characterized in that the removal in step 4 is to remove the outer layer of the fiber by calcination, and the specific process is: calcining the multi-component micro-nano fibers in a muffle furnace and cooling them naturally. The present invention achieves complete removal of the outer layer of the fiber without affecting the multi-component parallel micro-nano fibers by controlling the removal process.

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

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

[0027] 1. In view of the problem that the jet is prone to splitting when preparing multi-component parallel micro-nano fibers by the current electrospinning method, the present invention proposes to use the "core-wrapped" multi-fluid electrospinning technology, in which an external fluid wraps multiple internal fluids to stabilize the spinning process, and a post-treatment process is combined to remove the outer protective layer to obtain multi-component parallel micro-nano fibers.

[0028] 2 The multi-component parallel micro-nano fiber obtained by the present invention has a clear heterogeneous interface, which can not only retain the inherent properties of each component, but also have the synergistic effect of the heterogeneous interface. The method proposed by the present invention is conducive to improving the molding rate of the preparation of multi-component parallel micro-nano fibers, reducing the difficulty of preparation, broadening the applicable spinning system, and promoting the development of this multifunctional fiber.

[0029] 3. The method of multi-component parallel micro-nano fibers disclosed in the present invention comprises an outer fluid covering an inner fluid, a stable spinning process, and a high fiber forming rate.

[0030] 4. The present invention has a wide range of applicable systems. In terms of the number of components, it can be used to prepare double-parallel, triple-parallel, and quad-parallel fibers; in terms of structural regulation, it is suitable for preparing straight-line parallel, triangular parallel, square parallel, and other fibers.

[0031] 5. The multi-component parallel micro-nano fibers of the present invention can realize the composite of various materials and the integration of multiple functions, have a clear long-range heterogeneous interface, and have a wide range of applications in photocatalysis, electrocatalysis, electromagnetic shielding, biomedicine, etc.

[0032] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a physical picture of the outlet of the core-wrapped multi-fluid spinning spinneret when there are two internal fluid needles in Example 1 of the present invention.

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

[0035] Figure 3 This is a physical picture of the outlet of the core-wrapped multi-fluid spinning spinneret when there are three internal fluid needles in a straight line in Example 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-wrapped multi-fluid spinning spinneret when there are three internal fluid needles in the shape of a regular triangle in Example 5 of the present invention. DETAILED DESCRIPTION

[0038] Example 1

[0039] This embodiment includes the following steps:

[0040] Step 1: Prepare a core-wrapped dual-fluid spinning spinneret:

[0041] Two 20G inner fluid needles were bonded in a straight line using solder, and then placed at the geometric center of the 11G outer fluid needle, with the inner fluid needle outlet flush and protruding 0.1 mm from the outer fluid needle, and then fixed to obtain a core-wrapped dual-fluid spinning spinneret. Figure 1 ;

[0042] Step 2: Prepare spinning solution:

[0043] Dissolve polyvinyl pyrrolidone in N, N-dimethylacetamide and stir thoroughly until completely dissolved to obtain external fluid solution A with a concentration of 20%; dissolve polyacrylonitrile (PAN) in N, N-dimethylformamide and stir thoroughly in a 60°C water bath until completely dissolved to obtain internal fluid solution B1 , concentration is 15%; polystyrene (PS) is dissolved in N,N-dimethylformamide and stirred thoroughly until completely dissolved to obtain internal fluid solution B 2 , concentration is 25%;

[0044] Step 3: Prepare multi-component micro-nano fibers by multi-fluid spinning:

[0045] The spinneret obtained in step 1 is used to perform multi-fluid electrospinning, and the external fluid solution A obtained in step 2 is injected into the external fluid needle of the spinneret, and the internal fluid solution B is respectively 1 , B 2 The two inner fluid needles of the spinneret were injected, the flow rate of the outer fluid solution A was 1.2 mL / h, and the inner fluid solution B was 1 , B 2 The flow rate of each was 0.2 mL / h, and the flow rate ratio was 6:1. Then, a high-voltage electrostatic field was applied between the receiving substrate and the spinneret for multi-fluid spinning. 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-nano fibers were obtained on the receiving substrate.

[0046] Step 4: Remove the outer layer of the fiber to prepare the two-component parallel micro-nano fiber:

[0047] The multi-component micro-nano fibers obtained in step three were immersed in 200 mL of deionized water and ultrasonicated for 20 min. The deionized water was replaced after taking out, and the process was repeated three times and then dried to obtain PAN / PS two-component parallel micro-nano fibers.

[0048] Figure 2 The SEM image of the PAN / PS two-component parallel micro-nano fibers prepared in this example. Figure 2 It can be seen that the PAN / PS two-component parallel micro-nano fibers prepared in this embodiment have an obvious two-parallel fiber structure.

[0049] According to the test, the width of the PAN / PS two-component parallel micro-nano fibers prepared in this embodiment is 3 μm.

[0050] Example 2

[0051] This embodiment includes the following steps:

[0052] Step 1: Prepare a core-wrapped three-fluid spinning spinneret:

[0053] Three inner fluid needles of 22G are bonded in a straight line with solder, and then placed at the geometric center of the outer fluid needle of 10G, with the inner fluid needle outlet flush and protruding 0.5mm from the outer fluid needle, and then fixed to obtain a core-wrapped three-fluid spinning spinneret. Figure 3;

[0054] Step 2: Prepare spinning solution:

[0055] Dissolve polyvinyl butyral in N,N-dimethylacetamide and stir thoroughly until completely dissolved to obtain external fluid solution A with a concentration of 10%; dissolve polyacrylonitrile (PAN) in N,N-dimethylformamide and stir thoroughly in a 60°C water bath until completely dissolved to obtain internal fluid solution B 1 , concentration is 15%; polystyrene (PS) is dissolved in N,N-dimethylformamide and stirred thoroughly until completely dissolved to obtain internal fluid solution B 2 , concentration is 25%; polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) is dissolved in a solvent of acetone and N,N-dimethylacetamide with a mass ratio of 7:3 and stirred until completely dissolved to obtain an internal fluid solution B 3 , concentration is 15%;

[0056] Step 3: Prepare multi-component micro-nano fibers by multi-fluid spinning:

[0057] The spinneret obtained in step 1 is used to perform multi-fluid electrospinning, and the external fluid solution A obtained in step 2 is injected into the external fluid needle of the spinneret, and the internal fluid solution B is respectively 1 , B 2 , B 3 The three internal fluid needles of the spinneret, B 2 In B 1 With B 3 In the middle, the flow rate of the outer fluid solution A is 1.8 mL / h, and the flow rate of the inner fluid solution B is 1 , B 2 , B 3 The flow rate was 0.2 mL / h; the flow rate ratio was 9:1, and then a high-voltage electrostatic field was applied between the receiving substrate and the spinneret for multi-fluid spinning. 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, and multi-component micro-nano fibers were obtained on the receiving substrate.

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

[0059] The multi-component micro-nanofibers obtained in step three were immersed in 200 mL of anhydrous ethanol and ultrasonicated for 20 min. After being taken out, anhydrous ethanol was replaced. The process was repeated three times and then dried to obtain PAN / PS / PVDF-HFP three-component in-line parallel micro-nanofibers.

[0060] Figure 4 The SEM image of the PAN / PS / PVDF-HFP three-component parallel micro-nano fibers prepared in this example. Figure 4 It can be seen that the PAN / PS / PVDF-HFP three-component in-line parallel micro-nanofibers prepared in this embodiment have an obvious three-parallel fiber structure.

[0061] After testing, the width of the PAN / PS / PVDF-HFP three-component parallel micro-nano fibers prepared in this embodiment is 2.7 μm.

[0062] Example 3

[0063] This embodiment includes the following steps:

[0064] Step 1: Prepare a core-wrapped dual-fluid spinning spinneret:

[0065] Two inner fluid needles of 20G are bonded in a straight line with solder, and then placed at the geometric center of the outer fluid needle of 12G, with the outlet of the inner fluid needle flush and protruding 0.3mm from the outer fluid needle, and then fixed to obtain a core-wrapped dual-fluid spinning spinneret;

[0066] Step 2: Prepare spinning solution:

[0067] Polyvinyl pyrrolidone was dissolved in N,N-dimethylacetamide and stirred until completely dissolved to obtain an external fluid solution A with a concentration of 20%; 0.1 mmol of anhydrous copper acetate was dissolved in N,N-dimethylformamide, and then polyacrylonitrile (PAN) was added thereto and stirred in a 60°C water bath until completely dissolved to obtain an internal fluid solution B 1 , the polymer concentration is 15%; polystyrene (PS) is dissolved in N,N-dimethylformamide and stirred until completely dissolved, then 0.1mmol tetrabutyl titanate and 0.1mmol acetylacetone are added thereto, and stirring is continued until the solution is uniform to obtain the internal fluid solution B 2 , polymer concentration is 25%;

[0068] Step 3: Prepare multi-component micro-nano fibers by multi-fluid spinning:

[0069] The spinneret obtained in step 1 is used to perform multi-fluid electrospinning, and the external fluid solution A obtained in step 2 is injected into the external fluid needle of the spinneret, and the internal fluid solution B is respectively 1 , B 2 The two inner fluid needles injected into the spinneret, the flow rate of the outer fluid solution A was 2.0 mL / h, and the inner fluid solution B was 1 , B 2The flow rate was 1.0 mL / h, the flow rate ratio was 2:1, and then a high-voltage electrostatic field was applied between the receiving substrate and the spinneret for multi-fluid spinning. 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, and multi-component micro-nano fibers were obtained on the receiving substrate.

[0070] Step 4: Remove the outer layer of the fiber to prepare the two-component parallel micro-nano fiber:

[0071] The bicomponent micro-nano fibers obtained in step 3 were placed in a muffle furnace and heated from room temperature to 400°C at a rate of 2°C / min. After being kept at this temperature for 2 hours, they were naturally cooled to room temperature. Subsequently, they were placed in a tube furnace and heated under 10% Ar / H 2 The calcination was carried out under a molten-salt atmosphere, and the temperature was increased to 400°C at a rate of 2°C / min and kept at this temperature for 2 h to reduce CuO to Cu with photocatalytic activity. 2 O, Cu 2 O, and finally cooled naturally to room temperature to obtain Cu 2 O / TiO 2 Bicomponent parallel micro-nano fibers.

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

[0073] After testing, the Cu prepared in this example 2 O / TiO 2 The width of the two-component parallel micro-nanofiber is 500nm and is applied to photocatalytic reduction of CO 2 During the reaction, methanol can be selectively obtained with a selectivity greater than 80%.

[0074] Example 4

[0075] This embodiment includes the following steps:

[0076] Step 1: Prepare a core-wrapped three-fluid spinning spinneret:

[0077] Three inner fluid needles of 23G are bonded in a straight line with solder, and then placed at the geometric center of the outer fluid needle of 10G, with the inner fluid needle outlet flush and protruding 0.5mm from the outer fluid needle, and then fixed to obtain a core-wrapped three-fluid spinning spinneret;

[0078] Step 2: Prepare spinning solution:

[0079] Polyvinyl pyrrolidone was dissolved in N, N-dimethylacetamide and stirred until completely dissolved to obtain an external fluid solution A with a concentration of 20%; 0.1 mmol of bismuth chloride and 0.1 mmol of acetylacetonatovanadium were dissolved in N, N-dimethylformamide, and then polystyrene was added thereto and stirred until completely dissolved to obtain an internal fluid solution B. 1 , the polymer concentration is 25%; polyacrylonitrile (PAN) is dissolved in N,N-dimethylformamide to prepare a 15% solution to obtain the internal fluid solution B 2 ; Dissolve polystyrene in N,N-dimethylformamide and stir thoroughly until completely dissolved, then add 0.1mmol tetrabutyl titanate and 0.1mmol acetylacetone, and continue stirring until the solution is uniform to obtain internal fluid solution B 3 , polymer concentration is 25%;

[0080] Step 3: Prepare multi-component micro-nano fibers by multi-fluid spinning:

[0081] The spinneret obtained in step 1 is used to perform multi-fluid electrospinning, and the external fluid solution A obtained in step 2 is injected into the external fluid needle of the spinneret, and the internal fluid solution B is respectively 1 , B 2 , B 3 The three internal fluid needles of the spinneret, B 2 In B 1 With B 3 In the middle, the flow rate of the external fluid solution A is 2.0 mL / h, and the flow rate of the internal fluid solution B is 1 , B 2 , B 3 The flow rate was 0.66 mL / h, and the flow rate ratio was set to 3:1. Then, a high-voltage electrostatic field was applied between the receiving substrate and the spinneret for multi-fluid spinning. 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. Multi-component micro-nano fibers were obtained on the receiving substrate.

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

[0083] The multi-component micro-nano fibers obtained in step 3 were immersed in 200 mL of anhydrous ethanol and ultrasonicated for 20 min. After being taken out, new anhydrous ethanol was replaced. The process was repeated three times and then dried. Then, the fibers were placed in a muffle furnace and heated from room temperature to 280 °C at a rate of 2 °C / min for 2 h for pre-oxidation treatment. Finally, the fibers were placed in a tubular furnace and calcined in an Ar atmosphere. The fibers were heated to 700 °C at a rate of 2 °C / min for 2 h to obtain BiVO 4 / C / TiO 2 Three components of parallel micro-nano fibers in line.

[0084] After testing, the BiVO prepared in this example 4 / C / TiO 2 The width of the three-component parallel micro-nanofiber is 1 μm, which is applied to the photocatalytic reduction of CO 2 In the reaction, CH 4 , and the selectivity is greater than 85%.

[0085] Example 5

[0086] This embodiment includes the following steps:

[0087] Step 1: Prepare a core-wrapped three-fluid spinning spinneret:

[0088] Three inner fluid needles of 22G are bonded in an equilateral triangle using solder, and then placed at the geometric center of the outer fluid needle of 10G, with the inner fluid needle outlet flush and protruding 1mm from the outer fluid needle, and then fixed to obtain a core-wrapped three-fluid spinning spinneret. Figure 5 ;

[0089] Step 2: Prepare spinning solution:

[0090] Dissolve polyvinyl butyral in N,N-dimethylacetamide and stir thoroughly until completely dissolved to obtain external fluid solution A with a concentration of 10%; dissolve polyacrylonitrile (PAN) in N,N-dimethylformamide and stir thoroughly in a 60°C water bath until completely dissolved to obtain internal fluid solution B 1 , concentration is 15%; polystyrene (PS) is dissolved in N,N-dimethylformamide and stirred thoroughly until completely dissolved to obtain internal fluid solution B 2 , concentration is 25%; polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) is dissolved in a solvent of acetone and N,N-dimethylacetamide with a mass ratio of 7:3 and stirred until completely dissolved to obtain an internal fluid solution B 3 , concentration is 15%;

[0091] Step 3: Prepare multi-component micro-nano fibers by multi-fluid spinning:

[0092] The spinneret obtained in step 1 is used to perform multi-fluid electrospinning, and the external fluid solution A obtained in step 2 is injected into the external fluid needle of the spinneret, and the internal fluid solution B is respectively 1 , B 2 , B 3 The three internal fluid needles injected into the spinneret, the flow rate of the external fluid solution A was 1.0 mL / h, and the internal fluid solution B was 1 , B 2 , B 3 The flow rate was 0.11 mL / h, the flow rate ratio was 9:1, and then a high-voltage electrostatic field was applied between the receiving substrate and the spinneret for multi-fluid spinning. 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. Multi-component micro-nano fibers were obtained on the receiving substrate.

[0093] Step 4: Remove the outer layer of the fiber to prepare three-component equilateral triangle parallel micro-nano fibers:

[0094] The multi-component micro-nanofibers obtained in step three were immersed in 200 mL of anhydrous ethanol and ultrasonicated for 20 min. After being taken out, new anhydrous ethanol was replaced. The process was repeated three times and then dried to obtain PAN / PS / PVDF-HFP three-component equilateral triangle parallel micro-nanofibers.

[0095] According to the test, the width of the PAN / PS / PVDF-HFP three-component parallel micro-nano fibers prepared in this embodiment is 1.8 μm.

[0096] Example 6

[0097] This embodiment includes the following steps:

[0098] Step 1: Prepare a core-wrapped four-fluid spinning spinneret:

[0099] Four inner fluid needles of 23G are bonded in a straight line with solder, and then placed at the geometric center of an outer fluid needle of 10G, with the inner fluid needle outlet flush and protruding 0.5mm from the outer fluid needle, and then fixed to obtain a core-wrapped four-fluid spinning spinneret;

[0100] Step 2: Prepare spinning solution:

[0101] Dissolve polyvinyl pyrrolidone in N, N-dimethylacetamide and stir thoroughly until completely dissolved to obtain external fluid solution A with a concentration of 20%; dissolve polyacrylonitrile (PAN) in N, N-dimethylformamide and stir thoroughly in a 60°C water bath until completely dissolved to obtain internal fluid solution B 1 , concentration is 15%; polystyrene (PS) is dissolved in N,N-dimethylformamide and stirred thoroughly until completely dissolved to obtain internal fluid solution B 2, concentration is 25%; polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) is dissolved in a solvent of acetone and N,N-dimethylacetamide with a mass ratio of 7:3 and stirred until completely dissolved to obtain an internal fluid solution B 3 , the concentration is 15%; polyurethane (PU) is dissolved in a solvent of N,N-dimethylformamide and tetrahydrofuran with a mass ratio of 1:1 and stirred until completely dissolved to obtain internal fluid B 4 , concentration is 10%.

[0102] Step 3: Prepare multi-component micro-nano fibers by multi-fluid spinning:

[0103] The spinneret obtained in step 1 is used to perform multi-fluid electrospinning, and the external fluid solution A obtained in step 2 is injected into the external fluid needle of the spinneret, and the internal fluid solution B is respectively 1 , B 2 , B 3 , B 4 The flow rate of the external fluid solution A was 2.0 mL / h, and the flow rate of the internal fluid solution B was 2.0 mL / h. 1 , B 2 , B 3 , B 4 The flow rate of each was 0.3 mL / h, and the flow rate ratio was about 7:1. Then, a high-voltage electrostatic field was applied between the receiving substrate and the spinneret for multi-fluid spinning. 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. Multi-component micro-nano fibers were obtained on the receiving substrate.

[0104] Step 4: Remove the outer layer of the fiber to prepare the two-component parallel micro-nano fiber:

[0105] The multi-component micro-nano fibers obtained in step three were immersed in 200 mL of deionized water and ultrasonicated for 20 min. The deionized water was replaced after taking out, and the process was repeated three times and then dried to obtain PAN / PS / PVDF / PU two-component parallel micro-nano fibers.

[0106] After testing, it was found that the width of the PAN / PS / PVDF / PU four-component parallel micro-nano fibers prepared in this embodiment was 3 μm.

[0107] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing multi-component parallel micro-nano fibers, characterized in that: The method comprises the following steps: Step 1: Prepare a core-wrapped multi-fluid spinning spinneret: Assembling an external fluid needle and two or more internal fluid needles of matching models to obtain a core-wrapped multi-fluid spinning spinneret; Step 2: Prepare spinning solution: Dissolve the linear polymer a in the organic solvent a and stir thoroughly until it is completely dissolved to obtain an external fluid solution A with a concentration of 10% to 25%; Various linear polymers i Dissolve them in organic solvent B and stir them thoroughly until they are completely dissolved to obtain various internal fluid solutions B with concentrations of 10% to 20%. i ; Step 3: Prepare multi-component micro-nano fibers using multi-fluid spinning technology: Using the spinneret obtained in step 1 to perform multi-fluid electrospinning, injecting the external fluid solution A obtained in step 2 into the external fluid needle of the spinneret, respectively passing the multiple internal fluid solutions B obtained in step 2 into multiple internal fluid needles, and then applying a high-voltage electrostatic field between the receiving substrate and the spinneret to perform multi-fluid spinning, thereby obtaining multi-component micro-nano fibers on the receiving substrate; Step 4: Remove the outer layer of the fiber to prepare multi-component parallel micro-nano fibers: The outer layer of the multi-component micro-nano fiber obtained in step three is removed to obtain the multi-component parallel micro-nano fiber.

2. The method for preparing multi-component parallel micro-nano fibers according to claim 1, characterized in that: The specification of the outer fluid needle in step 1 is 10G~12G, and the specification of the inner fluid needle is 20G~23G. Multiple inner fluid needles are closely arranged in a straight line or a regular polygon. The inner fluid needle outlet is flush and protrudes from the outer fluid needle by 0.1mm~1mm, and is placed at the geometric center of the outer fluid needle.

3. The method for preparing multi-component parallel micro-nano fibers according to claim 1, characterized in that: In step 2, the linear polymer a is polyvinyl pyrrolidone or polyvinyl butyral, the organic solvent a is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, ethanol and acetone; the linear polymer b i It 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-nano fibers according to claim 1, characterized in that: The outer fluid solution A and the inner fluid solution B in step 2 i Precursor compounds are added, and the precursor compounds include tetrabutyl titanate, a precursor of TiO2, bismuth chloride and vanadium acetylacetonate, a precursor of BiVO4, and anhydrous copper acetate, a precursor of Cu2O.

5. The method for preparing multi-component parallel micro-nano fibers according to claim 1, characterized in that: The outer fluid solution A and the inner fluid solution B in step 3 i All are injected through a syringe pump, the flow rate of the external fluid solution A is recorded as x, the flow rate of the internal fluid solution B is recorded as y, the number of internal fluid needles is recorded as n, and x, y and n satisfy: n≤x / y≤3×n.

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

7. The method for preparing multi-component parallel micro-nano fibers according to claim 1, characterized in that: The removal described in step 4 is to remove the outer layer of the fiber by dissolving it in ethanol or water. The specific process is: when the component of the external fluid solution A is polyvinyl pyrrolidone, the multi-component micro-nano fiber is immersed in deionized water, and then ultrasonicated 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-nano fiber is immersed in anhydrous ethanol, and then ultrasonicated for more than 20 minutes, repeated three times and then dried.

8. The method for preparing multi-component parallel micro-nano fibers according to claim 1, characterized in that: The removal in step 4 is to remove the outer layer of the fiber by calcination, and the specific process is: calcine the multi-component micro-nano fiber in a muffle furnace and cool it naturally.

9. The method for preparing multi-component parallel micro-nano fibers according to claim 1, characterized in that: The adjacent parallel fibers in the multi-component parallel micro-nano fibers in step 4 have different compositions, the cross-sectional morphology of the multi-component parallel micro-nano fibers is a straight parallel structure or a regular polygonal parallel structure, and the width of the multi-component parallel micro-nano fibers is 500nm to 3μm.

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