A hollow functional fiber prepared based on impregnation and freeze-drying process and method thereof

Abstract

The present invention discloses a method for preparing hollow functional fibers based on an impregnation and freeze-drying process, comprising the following steps: (1) selecting a nano-dispersion liquid; (2) using a rotary collection technique to collect electrostatically spun glycerol-modified polyacrylonitrile fibers to prepare a fiber template with a millimeter diameter; and (3) using the fiber template in step (2) to impregnate the nano-dispersion liquid in step (1), adjusting the particle size and concentration, and freeze-drying the fibers to prepare porous hollow functional fibers. The hollow fibers of the present invention have abundant pores after impregnation, facilitating full gel infiltration, facilitating the preparation of fully gelled energy storage devices, and also utilizing the gel to protect the material inside the fibers.

Description

Technical Field

[0001] The invention belongs to the field of functional fibers, and in particular relates to a hollow functional fiber prepared based on an impregnation and freeze-drying process and a method thereof. Background Art

[0002] Hollow fibers have great application value in many fields such as energy storage, filtration, wave absorption and shielding. Taking the field of fibrous energy storage as an example, the dimensional electrodes derived from it can be prepared into fibrous energy storage devices. Their weaving and flexibility characteristics have become a hot development target for wearable energy storage. The impregnation process is the most efficient technical means to prepare fiber electrodes. It often prepares electrode materials by combining templates and active materials. The traditional preparation method uses wet-spun fibers as templates. However, due to the limitations of coagulation technology, the diameter of wet-spun fibers is only tens of microns and the specific surface area is small. The active substances loaded by the impregnation process are limited. Therefore, in the field of energy storage, its unit length capacity is very low and cannot meet practical applications. The process is as follows Figure 1 (a) In order to solve this problem, researchers use fiber bundle templates to load active substances. The process is as follows Figure 1 As shown in (b), the high specific surface area of ​​this template allows for increased loading of active materials. However, the template's excessively high packing density hinders gel infiltration, resulting in inadequate contact between the electrolyte and the active materials. Consequently, its gel-based all-solid-state energy storage devices exhibit interfering capacity and rate. Fluffy, fibrous aerogel templates are key to addressing these challenges. However, there are only two types of such templates, and they cannot be loaded with materials through an impregnation process. There are no reports on techniques for forming hollow fibers from them. Figure 1 (c) shows the advantages of the millimeter diameter hollow fiber over the other two types of fibers. The millimeter diameter hollow fiber prepared by the present invention has the advantages of high loading capacity and good gel impregnation. Summary of the Invention

[0003] The present invention provides a hollow functional fiber and a method thereof prepared based on an impregnation and freeze-drying process to fill the gap in this direction. The hollow functional fiber can be applied in many scenarios such as energy storage and filtration.

[0004] The fluffy fibrous aerogel template has a spatial structure that can carry a large amount of active substances. However, there are only two types of this template and it cannot be loaded with substances through the impregnation process. There are no reports on the technology of forming it into hollow fibers, and it is impossible to achieve gel liquid infiltration.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for preparing hollow functional fibers based on an impregnation and freeze-drying process comprises the following steps:

[0007] (1) Selecting a nanodispersion liquid;

[0008] (2) Using a rotary collection technique to collect electrospun glycerol-modified polyacrylonitrile fibers to prepare a fiber template;

[0009] (3) The nano-dispersion liquid in step (1) is impregnated with the fiber template in step (2), and porous hollow functional fibers are prepared by adjusting the particle size and concentration and freeze-drying process.

[0010] Furthermore, the nano-dispersion liquid in step (1) includes one or more of a carbon particle dispersion liquid and an iron oxide dispersion liquid.

[0011] Furthermore, the carbon particle dispersion is carbon nanoparticle dispersion BP2000.

[0012] Furthermore, the mass fraction of the carbon nanoparticle dispersion BP2000 is 5%, and the mass fraction of the iron oxide dispersion is 30%.

[0013] Furthermore, the particle size of the nano-dispersion liquid is within 100 nm.

[0014] Furthermore, the size of the nano-dispersion liquid is controlled at 2% to 20%.

[0015] Furthermore, the fiber template described in step (2) is a fiber template with a diameter of millimeters.

[0016] Furthermore, in step (2), a method for collecting electrospun glycerol-modified polyacrylonitrile fibers to prepare a fiber template using a rotary collection technology comprises the following steps: preparing a mixed solution of DMF and glycerol in a mass ratio of 5.7:0.6, dispersing 10% polyacrylonitrile by mass into the solution, heating it to 70°C to prepare a spinning liquid, and obtaining a fibrous aerogel template with a diameter of 1-5 mm by rotary collection.

[0017] Furthermore, the particle size in step (3) is less than 100 nm, which matches the diameter of the fiber.

[0018] Furthermore, the freeze drying in step (3) is carried out at -70°C for 20 to 30 minutes.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The hollow fiber prepared by the present invention adopts an impregnation and cold drying process which is simple and feasible;

[0021] (2) The loading amount and type of the hollow fiber of the present invention can be controlled to achieve multi-scenario application;

[0022] (3) The hollow fiber of the present invention has a good match between the material and the template. After impregnation, the fiber has abundant pores, which is conducive to the full infiltration of the gel and the preparation of a full gel energy storage device. The gel can also be used to protect the material inside the fiber. The principle diagram of its full coverage is shown in FIG. Figure 2 As shown;

[0023] (4) The present invention can only realize a hollow structure by selecting nanoparticles with a certain rigidity of appropriate size and concentration for filling, and make the overall fiber have good gel impregnation properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the advantage of this millimeter diameter hollow fiber over the other two types of fibers;

[0025] Figure 2 This is a schematic diagram of the principle that a millimeter diameter hollow fiber can be fully covered with gel;

[0026] Figure 3 3 is a scanning image of the hollow fiber filled with carbon nanoparticles prepared in Example 1. DETAILED DESCRIPTION

[0027] In an embodiment of the present invention, a method for preparing hollow functional fibers based on an impregnation and freeze-drying process comprises the following steps:

[0028] (1) Selecting a nano-dispersion liquid with a particle size of less than 100 nm, such as an iron oxide dispersion liquid, a carbon nanoparticle dispersion liquid, etc., wherein the size of the nano-dispersion liquid is controlled to be 2% to 20%;

[0029] (2) Using a rotary collection technique to collect electrospun glycerol-modified polyacrylonitrile fibers to prepare millimeter-diameter fiber templates;

[0030] (3) The nano-dispersion liquid in step (1) is impregnated with the fiber template in step (2), and porous hollow functional fibers are prepared by adjusting the particle size and concentration and freeze-drying process.

[0031] In order to make the disclosure of the present invention more complete, it is described below through more specific embodiments.

[0032] Example 1

[0033] A method for preparing hollow fibers based on an immersion freeze-drying process comprises the following steps:

[0034] The first step is to select a nano-dispersion liquid for the hollow fiber of carbon-based materials. The commercial carbon nanoparticle dispersion BP2000 is selected, with a particle size of less than 100 nm. The size of the nano-dispersion liquid is controlled at 10%.

[0035] The second step is to prepare the fiber template. First, DMF and glycerol are prepared into a mixed solution with a mass ratio of 5.7:0.6. 10% polyacrylonitrile is dispersed into the solution and heated to 70°C to prepare a spinning liquid. The spinning liquid is collected by rotating to obtain a fibrous aerogel template with a diameter of 1-5 mm.

[0036] The third step is to prepare porous carbon nanoparticle composite hollow functional fibers by infiltrating the prepared nano-dispersion, adjusting the particle size and concentration and freeze-drying process. The particle size is less than 100nm, matching the diameter of the fiber, and freeze-drying is carried out at -70℃ for 20 to 30 minutes.

[0037] Figure 3 This is a scan of a carbon nanoparticle composite hollow functional fiber after being impregnated with a carbon nanoparticle dispersion and lyophilized. It can be seen from the figure that it has a hollow structure.

[0038] Example 2

[0039] In the field of wave absorption, carbon nanoparticles are used as a dispersion liquid and are prepared according to the application scenario for use alone. The wave absorbing material is 30% by mass of ferroferric oxide mixed with 5% by mass of BP2000. The other steps are the same as those in Example 1, and the hollow fiber used for wave absorption is used.

[0040] Example 3

[0041] In the field of electromagnetic shielding, a mixed dispersion of carbon nanoparticles and ferroferric oxide is prepared and mixed according to the application scenario, with 30% ferroferric oxide mixed with 5% BP2000 by mass. Other steps are the same as in Example 1.

[0042] Example 4

[0043] For wave absorption, a dispersion of ferroferric oxide is prepared and used alone according to the application scenario. The wave absorbing material is 30% by mass of ferroferric oxide mixed with 5% by mass of BP2000. The other steps are the same as those in Example 1, and the hollow fiber used for wave absorption is used.

[0044] Example 5

[0045] Applied to the field of heat insulation, step 1 uses a mixed dispersion of PVP with a mass fraction of 5% and a mass fraction of 1%, and the other steps are the same as those in Example 1, which is used for heat insulating hollow fibers.

Claims

1. A method for preparing hollow functional fibers based on an impregnation and freeze-drying process, characterized in that: The following steps are involved: (1) Select nanodispersion; (2) Using the rotary collection technology to collect electrospun glycerol-modified polyacrylonitrile fibers to prepare fiber templates; (3) using the fiber template in step (2) to impregnate the nanodispersion in step (1), and preparing porous hollow functional fibers by adjusting the particle size and concentration and freeze-drying; The nano-dispersion liquid in step (1) includes one or more of a carbon particle dispersion liquid and a ferroferric oxide dispersion liquid; The carbon particle dispersion is carbon nanoparticle dispersion BP2000; The particle size of the nano-dispersion liquid is within 100 nm; The size of the nano-dispersion liquid is controlled at 2% to 20%; In step (3), freeze drying is performed at -70°C for 20 to 30 minutes.

2. The method for preparing hollow functional fibers based on an impregnation and freeze-drying process according to claim 1, characterized in that: The mass fraction of the carbon nanoparticle dispersion BP2000 is 5%, and the mass fraction of the ferroferric oxide dispersion is 30%.

3. The method for preparing hollow functional fibers based on an impregnation and freeze-drying process according to claim 1, characterized in that: The method for preparing a fiber template by collecting electrospun glycerol-modified polyacrylonitrile fibers using a rotary collection technology in step (2) comprises the following steps: preparing a mixed solution of DMF and glycerol in a mass ratio of 5.7:0.6, dispersing 10% polyacrylonitrile by mass into the mixed solution, heating to 70°C to prepare a spinning liquid, and obtaining a fibrous aerogel template with a diameter of 1-5 mm by rotary collection.

4. The method for preparing hollow functional fibers based on an impregnation and freeze-drying process according to claim 1, wherein: The particle size described in step (3) is less than 100 nm, which matches the diameter of the fiber.

5. A hollow functional fiber prepared according to the preparation method according to any one of claims 1 to 4.

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