Polymer aerogel fibers and methods of making and using the same

Abstract

The application discloses a polymer aerogel fiber and a preparation method and application thereof. The polymer aerogel fiber is prepared from a polymer solution through a wet spinning method in a non-solvent phase separation principle through a phase separation bath and a coagulation bath, and the polymer nascent fiber is dried to obtain the polymer aerogel fiber. The preparation method of the polymer aerogel fiber has the advantages of simplicity, safety, environmental protection, rapidness and low cost, and provides a feasible scheme for preparing the aerogel fiber on a large scale at room temperature and under normal pressure. The obtained aerogel fiber has great application prospects in the directions of heat insulation, fire resistance and flame resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aerogel preparation, in particular to a polymer aerogel fiber and a preparation method and application thereof. BACKGROUND

[0002] Aerogel is a new type of material with high porosity, low density, large specific surface area and good thermal insulation performance. Aerogel fiber, which combines the advantages of aerogel and fiber material, is a lightweight, porous and flexible multifunctional material with wide application prospects in thermal insulation, pollution adsorption, biomedicine, energy storage and aerospace. Compared with bulk aerogel, aerogel fiber has high flexibility and can be easily integrated into various shapes and sizes of applications.

[0003] The existing preparation of aerogel fiber still continues the traditional process similar to bulk aerogel, i.e. sol-gel method, and then takes the method of freeze-drying or supercritical drying. This process has two major defects. On the one hand, as a non-continuous method, the drying conditions take a long time and the process is difficult to operate continuously, which does not have the prospect of large-scale continuous production. On the other hand, the freeze-drying and supercritical drying methods have high cost and high equipment requirements, which greatly limits the low-cost scale application of aerogel fiber. SUMMARY

[0004] In view of the defects of the existing technology that the preparation of aerogel fiber inevitably needs freeze-drying or supercritical drying, the present application provides a preparation method of polymer aerogel fiber, which overcomes the problems of traditional aerogel fiber process, such as complicated process, non-continuity, high cost and many restrictions.

[0005] One of the technical solutions of the present application is to provide a preparation method of polymer aerogel fiber. The traditional coagulation bath is divided into a phase separation bath and a coagulation bath. The phase separation bath uses a higher concentration of solvent to promote the delayed phase separation behavior of the polymer in the bath and avoid instantaneous phase separation, thereby forming a uniform sub-micron sponge pore structure. The coagulation bath composed of pure non-solvent can effectively maintain the sponge pore structure, so that the polymer aerogel can be obtained by room temperature and normal pressure drying without additional freeze-drying or supercritical drying, thereby realizing large-scale continuous spinning. In addition, compared with the existing freeze-drying method for fixing the pore structure, the present application can maintain a continuous sponge pore structure and ensure the strength of the aerogel fiber.

[0006] Specifically, the method comprises: extruding the polymer solution through a phase separation bath to obtain a gel-state fiber, and then passing the gel-state fiber through a coagulation bath to obtain a nascent fiber, and drying the nascent fiber to obtain the aerogel fiber; the phase separation bath is a mixed solution of a solvent of the polymer and a non-solvent, and the mass fraction of the solvent of the polymer is 40% to 90%; the phase separation time is 2 minutes to 10 minutes; and the coagulation bath is a non-solvent of the polymer.

[0007] Further, the polymer solution is a 10wt%-15wt% polyimide acid solution, a 0.1wt%-2.5wt% heterocyclic aramid solution, a 15wt%-25wt% polyurethane solution, or a 15wt%-25wt% polyacrylonitrile solution.

[0008] Further, the solvent is one or more of DMF, DMAC, NMP, DMSO, HMPA, TEP, TMP, and TMU, and the non-solvent is one or more of water, ethanol, isopropanol, methanol, diethyl ether, ethyl acetate, ethylene glycol, and glycerol.

[0009] Further, the drying process is room-temperature normal-pressure drying.

[0010] In some embodiments of the present application, polyimide acid is used as the polymer solution to prepare polyimide aerogel fibers, and the polyimide acid aerogel fibers need to be moved to a tube furnace for imidization at 300°C for one hour after drying to obtain polyimide aerogel fibers.

[0011] The second technical solution of the present application provides the polymer aerogel fiber prepared by the above method, wherein the polymer aerogel fiber has a thickness of 50 µm to 500 µm and a strength of 10 Mpa to 40 Mpa.

[0012] Further, the pores in the polymer aerogel fiber are micron-level sponge pores or nanometer-level sponge pores, and the average pore size is 500 nm to 5 µm.

[0013] The third technical solution of the present application provides the application of the above polymer aerogel fiber in the heat-resistant and fireproof field.

[0014] The fourth technical solution of the present application provides a fiber bundle prepared from the above polymer aerogel fiber.

[0015] The present application has the following beneficial effects: compared with the preparation of traditional aerogel fibers, the process does not need to go through solvent replacement or freeze drying, and the prepared fibers have uniform sponge pores, which on the one hand endows the fibers with good mechanical properties and flexibility under the condition of low density, and on the other hand the structure of the sponge pores is well maintained during the drying and heat treatment processes. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 SEM image of the polyimide aerogel fiber obtained in Example 1;

[0017] Figure 2 SEM image of the polyimide aerogel fibers obtained in Example 1;

[0018] Figure 3 This is a pore size distribution diagram of the polyimide aerogel obtained in Example 1;

[0019] Figure 4 Fire resistance test of polyimide aerogel in Example 1;

[0020] Figure 5 Image showing the knotted polyimide aerogel in Example 1;

[0021] Figure 6 SEM image of polyimide aerogel fibers in Example 2;

[0022] Figure 7 SEM image of polyimide aerogel fibers in Example 4;

[0023] Figure 8 The image shows a SEM image of the polyimide aerogel fiber obtained in Comparative Example 1. Detailed Implementation

[0024] Solvent-inducing phase separation is a common and fundamental scientific principle in the field of polymer membrane materials. The process involves dissolving the polymer in a solvent to form a homogeneous solution. Then, a reagent with stronger miscibility with the solvent (called an extractant) is slowly added to extract the solvent, resulting in a two-phase structure with the polymer as the continuous phase and the solvent as the dispersed phase. The solvent is then removed by atmospheric pressure drying, yielding a polymer with a specific porous structure. This method is widely used in the preparation of phase-separated membranes and hollow fiber membranes. Furthermore, utilizing the principle of solvent-inducing phase separation for wet spinning followed by atmospheric pressure drying can effectively achieve continuous production of aerogel fibers.

[0025] The selection of polymer solvents and non-solvents is common knowledge in the field. Generally, the polymer solvent is selected from one or more of DMF, DMAC, NMP, DMSO, HMPA, TEP, TMP, and TMU, and the non-solvent is selected from one or more of water, ethanol, isopropanol, methanol, diethyl ether, ethyl acetate, ethylene glycol, and glycerol.

[0026] Sponge-like porous structures refer to a type of three-dimensional porous structure with uniform small pores, similar to a sponge.

[0027] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all figures are expressed in parts by weight and weight percentages.

[0028] The raw materials used in the present application are all conventional commercially available products unless otherwise specified; the methods used in the present application are all conventional methods in the art unless otherwise specified.

[0029] The embodiments of the present application are further described in the following examples.

[0030] It should be understood that the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor fall within the scope of protection of the present application.

[0031] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0032] Example 1

[0033] (1) 15wt% of polyimide acid N,N-dimethylacetamide solution was extruded to a phase separation bath using a spinning needle with an inner diameter of 340µm (corresponding to national standard 23G), and then drawn into a coagulation bath to obtain polyimide acid nascent fiber. The phase separation bath consists of N,N-dimethylacetamide and water in a mass ratio of 1:1, the phase separation time is 2 minutes, and the coagulation bath is water.

[0034] (2) The polyimide acid fiber was dried at room temperature and normal pressure to obtain a polyimide acid aerogel fiber, as shown in Figure 1 .

[0035] (3) The polyimide acid aerogel fiber was imidized to obtain a polyimide aerogel, the imidization temperature was 300℃, and the imidization time was 1h, as shown in Figure 2 .

[0036] Figure 3 The porosity distribution graph of the polyimide aerogel fiber in Example 1 shows that the pores of the aerogel fiber are normally distributed in the range of 1.5-3µm, and the proportion is greater than 70%. The polyimide aerogel fiber in Example 1 was subjected to ablation test, and the results are shown in Figure 4 . The polyimide aerogel fiber in Example 1 was knotted, and the results are shown in Figure 5 , proving that the aerogel fiber has good flexibility and weavability

[0037] Example 2

[0038] Example 2 differs from Example 1 in that the composition of the phase separation bath is N,N-dimethylacetamide and water in a mass ratio of 4:6, and the micro-morphology of the aerogel fibers obtained is as shown in Figure 6 The phase separation time is 10 minutes, the pore size is relatively uniform, the overall normal distribution is greater than 70% in the range of 400 nm-600 nm, and the average pore size is 500 nm. The fiber thickness is 50 pm, and the strength is 10 MPa.

[0039] Example 3

[0040] (1) Different from Example 1, a spinneret with a pore size of 240 pm and a number of 20 is used instead of a spinning needle to extrude into a phase separation bath and then drawn into a coagulation bath to obtain a polyimide acid primary fiber bundle. The composition of the phase separation bath is N,N-dimethylacetamide and water in a mass ratio of 1:1, the phase separation time is 2 minutes, and the coagulation bath is water.

[0041] (2) The polyimide acid fiber bundle is dried at room temperature and normal pressure to obtain a polyimide acid aerogel fiber bundle.

[0042] (3) The polyimide acid aerogel fiber bundle is heat imidized to obtain a polyimide aerogel fiber bundle, the imidization temperature is 300°C, and the imidization time is 1h.

[0043] (4) The obtained polyimide aerogel fiber bundle is woven into a plain fabric. The obtained fabric has good thermal insulation performance in the vertical direction, and the thermal conductivity is 44 mW / m·K.

[0044] Example 4

[0045] Compared with Example 1, this embodiment uses multiple spinning needles with different inner diameters (corresponding to national standards 22G, 24G, 28G, and 32G) to spin respectively, successfully realizing the preparation of aerogel fibers with different diameters. The micro-morphology of the obtained aerogel fibers with different diameters is as shown in Figure 7 .

[0046] Example 5

[0047] The difference from Example 1 is only that a 10wt% polyimide acid solution is used.

[0048] Example 6

[0049] (1) A 0.1wt% heterocyclic aramid N,N-dimethylacetamide solution is extruded into a phase separation bath using a national standard 21G spinning needle, and then drawn into a coagulation bath to obtain a heterocyclic aramid primary fiber. The mass composition of the phase separation bath is 80% dimethyl sulfoxide and 20% water, the phase separation time is 2 minutes, and the composition of the coagulation bath is ethanol.

[0050] (2) The heterocyclic aramid primary fiber is dried at room temperature and normal pressure to obtain a heterocyclic aramid aerogel fiber, the pore size of which is normally distributed in the range of 500 nm-1 µm, and the proportion of which is greater than 70%. The fiber is 500 µm thick, and the strength is 40 MPa. The average pore size is 5 µm.

[0051] Example 7

[0052] The difference from Example 6 is only that 2.5 wt% heterocyclic aramid solution is used.

[0053] Example 8

[0054] (1) A 15 wt% polyurethane dimethyl sulfoxide solution is extruded to a phase separation bath using a spinning needle of national standard 26G, and then drawn into a coagulation bath to obtain a polyurethane primary fiber. The mass composition of the phase separation bath is 40% N,N-dimethylacetamide solution and 60% water, and the phase separation time is 5 minutes. The coagulation bath is composed of ethanol and water in a 1:1 mutual solubility.

[0055] (2) The polyurethane primary fiber is dried at room temperature and normal pressure to obtain a polyurethane aerogel fiber, the pore size of which is normally distributed in the range of 2.5 µm-3.5 µm, and the proportion of which is greater than 70%. The fiber is 200 µm thick, and the strength is 40 MPa.

[0056] Example 9

[0057] The difference from Example 8 is only that 25 wt% polyurethane solution is used.

[0058] Example 10

[0059] (1) A 15 wt% polyacrylonitrile N,N-dimethylformamide solution is extruded to a phase separation bath using a spinning needle of national standard 32G, and then drawn into a coagulation bath to obtain a polyurethane primary fiber. The mass composition of the phase separation bath is 90% N-methyl pyrrolidone solution and 10% water, and the phase separation time is 2 minutes. The coagulation bath is composed of water.

[0060] (2) The polyacrylonitrile primary fiber is dried at room temperature and normal pressure to obtain a polyacrylonitrile aerogel fiber, the pore size of which is normally distributed in the range of 1 µm-2 µm, and the proportion of which is greater than 70%.

[0061] Example 11

[0062] The difference from Example 10 is only that 25 wt% polyacrylonitrile solution is used.

[0063] Example 12

[0064] The difference from Example 10 is only that the phase separation bath is 80% N-methyl pyrrolidone solution and 20% water.

[0065] Comparative Example 1

[0066] The only difference from Example 1 is that the composition of the phase separation bath is N,N-dimethylacetamide and water with a mass ratio of 1:4, the phase separation time is 2 minutes, and the coagulation bath is N,N-dimethylacetamide solution and water with a mass ratio of 1:9. The micro-morphology of the obtained aerogel fiber is shown in FIG. 2. It can be seen from the figure that the aerogel is mostly uneven finger-shaped holes with a length of 50 µm, and the fiber strength is low, the flexibility is poor, the tensile strength is about 5 MPa, and the elongation at break is about 10%. It can be seen that the appropriate concentration of the phase separation bath and the coagulation bath is the key to building uniform sub-micron sponge pores. Figure 8

[0067] Comparative Example 2

[0068] The difference from Example 1 is that after the phase separation bath of Example 1, it does not enter the coagulation bath, but directly freeze-drying. The pore size of the obtained aerogel fiber is wide distribution, between 1-10 µm, which will be not conducive to its industrial application.

[0069] The above examples illustrate the structure, features and effects of the present application. The above description is only the preferred embodiment of the present application. Any changes or modifications made in accordance with the concept of the present application, or equivalent embodiments with equivalent changes, shall be within the scope of the present application.​

Claims

1. A method of making a polymeric aerogel fiber, characterized by, The polymer solution is extruded through a phase separation bath to obtain a gel fiber, and then the gel fiber is subjected to a coagulation bath to obtain a nascent fiber, and the nascent fiber is dried to obtain an aerogel fiber; the phase separation bath is a mixed solution of a solvent of the polymer and a non-solvent, and the mass fraction of the solvent of the polymer is 40% to 90%; the phase separation time is 2 minutes to 10 minutes; the coagulation bath is a non-solvent of the polymer; the polymer solution is a 10wt% to 15wt% polyimide acid solution, a 0.1wt% to 2.5wt% heterocyclic aramid solution, a 15wt% to 25wt% polyurethane solution, or a 15wt% to 25wt% polyacrylonitrile solution; the solvent is one or more of DMF, DMAC, NMP, DMSO, HMPA, TEP, TMP, and TMU, and the non-solvent is one or more of water, ethanol, isopropyl alcohol, methanol, diethyl ether, ethyl acetate, ethylene glycol, and glycerol.

2. The production method according to claim 1, characterized by, The drying process is carried out at room temperature and under normal pressure.

3. A polymer aerogel fiber prepared by the method of claim 1, wherein, The polymer aerogel fiber has a thickness of 50µm to 500µm and a strength of 10Mpa to 40Mpa.

4. The polymeric aerogel fiber of claim 3, wherein, The pores in the polymer aerogel fiber are micron-level sponge pores or nanometer-level sponge pores, and the average pore size is 500nm to 5µm.

5. Use of the polymer aerogel fiber according to claim 3 in the field of heat resistance and fire prevention.

6. A fiber bundle composed of the polymer aerogel fiber according to any one of claims 1 to 5.

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