A method for producing an electrically conductive hollow cellulose fiber

Abstract

The application discloses a preparation method of conductive hollow cellulose fibers, which comprises the following steps: adding a covalent organic framework (COFs) precursor into a cellulose fiber spinning solution, then using a dry-wet spinning method to prepare the hollow cellulose fibers, and further generating the COFs in situ on the hollow cellulose fibers to obtain the conductive hollow cellulose fibers. Based on the directional pore structure of the hollow cellulose fibers, the COFs grow along the hollow cellulose fibers in a directional manner, forming ion transfer channels, so that the hollow cellulose fibers have excellent ion conduction capacity. The application realizes one-step efficient preparation of the conductive hollow cellulose fibers, and the operation is simple, and the obtained conductive hollow cellulose fibers have high ion conductivity.

Description

Technical Field

[0001] This invention belongs to the field of textile materials, and specifically relates to a method for preparing conductive hollow cellulose fibers. Background Technology

[0002] Hollow cellulose fibers have a fine tubular cavity structure along the fiber axis, which can contain a large amount of air, giving textiles good moisture permeability and warmth retention. They can be used in winter clothing, thermal underwear, and outdoor sportswear. Furthermore, their unique hollow cellulose walls exhibit selective permeability, making them suitable for separation, catalysis, ultrafiltration, controlled release, dialysis, sensing, and gas separation. Hollow cellulose fibers prepared by dissolving NMMO as a solvent can be applied in oil-water separation, dialysis, gas permeation, and membrane sensors. However, practical applications require high responsiveness from hollow cellulose fiber sensing materials; therefore, improving and enhancing the conductivity of hollow cellulose fibers is a pressing problem that needs to be solved.

[0003] The unique nanoporous structure and highly controllable pore chemistry within two-dimensional covalent organic frameworks (COFs) crystals offer the possibility of high-speed ion transport. However, currently prepared COFs are mostly powders with poor solubility. The randomly oriented ion channels of COFs and the boundaries between COF lamellar crystals hinder ion transport, weakening the ion transport efficiency in COF powders. This invention incorporates COF precursors into cellulose fiber spinning solutions, using hollow cellulose fibers as templates to generate oriented COFs in situ on the hollow cellulose fibers, forming interconnected ion transport channels. This endows hollow cellulose fibers with excellent ion conductivity, thereby improving their electrical conductivity. Summary of the Invention

[0004] To address the shortcomings of existing hollow cellulose fibers, this invention provides a method for preparing conductive hollow cellulose fibers, which imparts excellent ion conductivity to hollow cellulose fibers by generating oriented COFs in situ on the hollow cellulose fibers.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A conductive hollow cellulose fiber, the preparation method of which includes the following steps: (1) Add p-phenylenediamine to N-methylmorpholine-N-oxide (NMMO), stir and mix evenly, then add cellulose fiber, and stir at a certain temperature until the cellulose fiber dissolves to form a cellulose fiber solution; (2) The obtained cellulose fiber solution is degassed under vacuum at a certain temperature and then spun to form hollow cellulose fibers; (3) After the spun hollow cellulose fibers are washed with water and dried under vacuum at room temperature, they are placed in a mixture of trialdehyde phloroglucinol / acetic acid / dichloromethane and heated for a certain time to generate covalent organic frameworks (COFs) in situ on the hollow cellulose fibers. Then, they are washed with dichloromethane and acetone in sequence and dried under vacuum to obtain conductive hollow cellulose fibers.

[0006] Furthermore, the mass ratio of p-phenylenediamine to N-methylmorpholine-N-oxide used in step (1) is 1:3-1:6.

[0007] Furthermore, the cellulose fiber mentioned in step (1) is any one of bamboo fiber, cotton fiber, or hemp fiber.

[0008] Furthermore, the temperature used to dissolve the cellulose fibers in step (1) is 90-110℃.

[0009] Furthermore, the mass concentration of cellulose fibers in the cellulose fiber solution obtained in step (1) is 10%-13%.

[0010] Furthermore, the vacuum degassing temperature in step (2) is 80-100℃ and the time is 8-11h.

[0011] Furthermore, in step (2), the hollow cellulose fiber is specifically obtained by dry and wet spinning of the cellulose fiber solution under the conditions of pressure 0.5MPa and temperature 110℃ using a coaxial spinneret.

[0012] Furthermore, the mass ratio of hollow cellulose fiber to trialdehyde phloroglucinol / acetic acid / dichloromethane mixture used in step (3) is 1:400, wherein the mass ratio of hollow cellulose fiber to trialdehyde phloroglucinol and acetic acid is 1:1:10.

[0013] Furthermore, the heating reaction in step (3) is carried out at a temperature of 125-140°C for 8-10 hours.

[0014] This invention involves adding different covalent organic framework precursor monomers during the spinning stage and after spinning of cellulose hollow fibers. This allows different monomers to generate covalent organic framework materials in situ within the cavities of the hollow fibers. The hollow structure of the hollow fibers enables the covalent organic framework materials to grow in a confined space. At the same time, the directional arrangement characteristics of the hollow fiber cavity structure allow the generated covalent organic framework materials to produce highly ordered ion transport channels, giving the hollow fibers excellent ion conductivity.

[0015] The significant advantages of this invention are: This invention introduces covalent organic frameworks (COFs) precursors into the cellulose fiber spinning solution, thereby generating oriented COFs in situ on the hollow cellulose fibers during the spinning process. This forms ion transport channels, endowing the hollow cellulose fibers with excellent ion conductivity. This invention achieves a one-step, highly efficient preparation of conductive hollow cellulose fibers, with simple operation and high ionic conductivity. Attached Figure Description

[0016] Figure 1 The image shows a scanning electron microscope (SEM) image of the surface of the conductive hollow cellulose fibers prepared in Example 1. Figure 2 The image shows the internal pore size of the conductive hollow cellulose fiber prepared in Example 1 using a scanning electron microscope. Figure 3 The image shows a cross-sectional scanning electron microscope image of the hollow cellulose fibers prepared for Comparative Example 1. Detailed Implementation

[0017] A conductive hollow cellulose fiber, the preparation method of which includes the following steps: (1) Add p-phenylenediamine to N-methylmorpholine-N-oxide (water content 13wt%) at a mass ratio of 1:3-1:6, stir and mix evenly, then add cellulose fiber, stir at 90-110℃ until the cellulose fiber dissolves to form a cellulose fiber solution containing 10wt%-13wt% cellulose fiber; (2) After the obtained cellulose fiber solution is vacuum degassed at 80-100℃ for 8-11h, it is placed in a hollow cellulose fiber spinning equipment. Under the conditions of pressure 0.5MPa and temperature 110℃, hollow cellulose fibers are obtained by dry and wet spinning (water bath curing molding) using a coaxial spinneret. (3) The spun hollow cellulose fibers are washed with water and vacuum dried at room temperature for 24 hours. They are then placed in a mixture of trialdehyde phloroglucinol / acetic acid / dichloromethane at a solid-liquid mass ratio of 1:400, so that the mass ratio of hollow cellulose fibers to trialdehyde phloroglucinol and acetic acid is 1:1:10. The mixture is heated at 125-140℃ for 8-10 hours to generate covalent organic frameworks (COFs) in situ on the hollow cellulose fibers. The fibers are then washed with dichloromethane and acetone in sequence and vacuum dried at 50℃ for 18 hours to obtain conductive hollow cellulose fibers.

[0018] In step (1), the cellulose fiber is any one of bamboo fiber, cotton fiber, or hemp fiber.

[0019] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0020] Example 1 (1) Take 5g of p-phenylenediamine and add it to 30g of N-methylmorpholine-N-oxide (NMMO) with a water content of 13%. Stir and mix evenly. Then add 5g of cotton fiber to the mixture and stir at 110℃ until dissolved to prepare a cellulose fiber solution with a concentration of 12.5%. (2) The obtained cellulose fiber solution was degassed under vacuum at 100℃ for 8 hours, and then placed in a hollow cellulose fiber spinning equipment. Under the conditions of pressure 0.5MPa and temperature 110℃, dry and wet spinning (water bath curing) was carried out using a coaxial spinneret to form hollow cellulose fibers. (3) After washing the spun hollow cellulose fibers with water and drying them under vacuum at room temperature for 24 hours, 3g of hollow cellulose fibers were placed in a mixture of 1200g of trialdehyde phloroglucinol / acetic acid / dichloromethane (containing 3g of trialdehyde phloroglucinol and 30g of acetic acid) and reacted at 140℃ for 8 hours to generate covalent organic frameworks (COFs) in situ on the hollow cellulose fibers. Then, the fibers were washed with dichloromethane and acetone respectively and dried under vacuum at 50℃ for 18 hours to obtain conductive hollow cellulose fibers.

[0021] The surface scanning electron microscope image of the obtained conductive hollow cellulose fibers is shown below. Figure 1 As shown. By Figure 1 It can be seen that COFs grow in situ on hollow cellulose fibers and are oriented along the axial direction of the hollow cellulose fibers.

[0022] Example 2 (1) Take 10g of p-phenylenediamine and add it to 50g of N-methylmorpholine-N-oxide (NMMO) with a water content of 13%. Stir and mix evenly. Then add 7g of bamboo fiber to the mixture and stir at 100℃ until dissolved to prepare a cellulose fiber solution with a concentration of 10.45%. (2) The obtained cellulose fiber solution was degassed under vacuum at 90°C for 11 hours, and then placed in a hollow cellulose fiber spinning equipment. Under the conditions of pressure 0.5MPa and temperature 110°C, dry and wet spinning (water bath curing) was carried out using a coaxial spinneret to form hollow cellulose fibers. (3) After washing the spun hollow cellulose fibers with water and drying them under vacuum at room temperature for 24 hours, 5g of hollow cellulose fibers were placed in a mixture of 2000g of trialdehyde phloroglucinol / acetic acid / dichloromethane (containing 5g of trialdehyde phloroglucinol and 50g of acetic acid) and reacted at 130℃ for 10 hours to generate covalent organic frameworks (COFs) in situ on the hollow cellulose fibers. The fibers were washed with dichloromethane and acetone respectively and dried under vacuum at 50℃ for 18 hours to obtain conductive hollow cellulose fibers.

[0023] Scanning electron microscope (SEM) images of the interior pores of the obtained conductive hollow cellulose fibers are shown below. Figure 2 As shown. By Figure 2 It can be seen that COFs are attached to the inner wall of the hollow cellulose fiber cavity, and the COFs are oriented along the axial direction of the hollow cellulose fiber.

[0024] Comparative Example 1 (1) Take 5g of cotton fiber and add it to 35g of N-methylmorpholine-N-oxide (NMMO) with a water content of 13%, stir at 110℃ until dissolved, and prepare a cellulose fiber solution with a concentration of 12.5%; (2) The obtained cellulose fiber solution was degassed under vacuum at 100℃ for 8 hours, and then placed in a hollow cellulose fiber spinning equipment. Under the conditions of pressure 0.5MPa and temperature 110℃, dry and wet spinning (water bath curing) was carried out using a coaxial spinneret to form hollow cellulose fibers. (3) Take 10g of p-phenylenediamine and add it to 2000g of trialdehyde phloroglucinol / acetic acid / dichloromethane mixture (containing 5g of trialdehyde phloroglucinol and 50g of acetic acid). React at 130℃ for 10h to obtain a covalent organic framework (COFs) solution. (4) After washing the spun hollow cellulose fiber with water and drying it under vacuum at room temperature for 24 hours, take 3g of hollow cellulose fiber and immerse it in the prepared covalent organic framework solution for 24 hours, and then dry it under vacuum at 50°C for 18 hours to obtain conductive hollow cellulose fiber.

[0025] The cross-sectional scanning electron microscope image of the obtained hollow cellulose fibers is shown below. Figure 3 As shown. By Figure 3 It is known that hollow cellulose fibers have finger-like pores and sponge-like pores, with a cavity diameter of about 300 μm.

[0026] Comparative Example 2 (1) Take 5g of p-phenylenediamine and add it to 30g of N-methylmorpholine-N-oxide (NMMO) with a water content of 13%. Stir and mix evenly. Then add 5g of cotton fiber to the mixture and stir at 110℃ until dissolved to prepare a cellulose fiber solution with a concentration of 12.5%. (2) The obtained cellulose fiber solution was degassed under vacuum at 100°C for 8 hours, and then wet-spun (water bath curing) was performed under the conditions of 0.5 MPa pressure and 110°C to form cellulose fibers. (3) After washing the spun cellulose fibers with water and drying them under vacuum at room temperature for 24 hours, 3g of cellulose fibers were placed in a mixture of 1200g of trialdehyde phloroglucinol / acetic acid / dichloromethane (containing 3g of trialdehyde phloroglucinol and 30g of acetic acid) and reacted at 140℃ for 8 hours to generate covalent organic frameworks (COFs) in situ on the surface of the cellulose fibers. Then, the fibers were washed with dichloromethane and acetone respectively and dried under vacuum at 50℃ for 18 hours to obtain conductive cellulose fibers.

[0027] The properties of the hollow cellulose fibers prepared in each embodiment and comparative example were tested, and the results are shown in Table 1.

[0028] Table 1 Performance Tests of Different Hollow Cellulose Fibers

[0029] As shown in Table 1, the conductive hollow cellulose fibers obtained in the examples have a conductivity of up to 9 S / m, exhibiting good conductivity. This is mainly due to the oriented COFs attached to the hollow cellulose fibers in the examples, forming ion transport channels that promote efficient ion transport, resulting in high conductivity. In contrast, the conductivity of the hollow cellulose fibers in Comparative Example 1 is much lower than that in the examples. This is because COFs easily aggregate to form COF powder, which not only reduces their bonding ability with hollow cellulose fibers but also hinders ion transport due to the boundaries between randomly oriented lamellar crystals in the COF powder. The lower conductivity of Comparative Example 2 compared to the examples is because the non-hollow cellulose fibers lack the oriented cavity structure, preventing COFs from achieving confined growth and forming highly ordered ion transport channels. This results in random orientation of the ion channels in the COFs, severely affecting ion transport efficiency.

[0030] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing conductive hollow cellulose fibers, characterized in that: Includes the following steps: (1) Add p-phenylenediamine to N-methylmorpholine-N-oxide, stir and mix evenly, then add cellulose fiber, stir at a certain temperature until the cellulose fiber dissolves to form a cellulose fiber solution; (2) The obtained cellulose fiber solution is degassed under vacuum at a certain temperature and then spun to form hollow cellulose fibers; (3) After the spun hollow cellulose fibers are washed with water and dried under vacuum at room temperature, they are placed in a mixture of trialdehyde phloroglucinol / acetic acid / dichloromethane and heated for a certain time to generate a covalent organic framework on the hollow cellulose fibers in situ. Then, they are washed with dichloromethane and acetone in sequence and dried under vacuum to obtain conductive hollow cellulose fibers. The vacuum degassing temperature in step (2) is 80-100℃, and the time is 8-11h; The heating reaction in step (3) is carried out at a temperature of 125-140℃ for 8-10 hours.

2. The method for preparing conductive hollow cellulose fibers according to claim 1, characterized in that: The mass ratio of p-phenylenediamine to N-methylmorpholine-N-oxide used in step (1) is 1:3-1:

6.

3. The method for preparing conductive hollow cellulose fibers according to claim 1, characterized in that: The cellulose fiber mentioned in step (1) can be any one of bamboo fiber, cotton fiber, or hemp fiber.

4. The method for preparing conductive hollow cellulose fibers according to claim 1, characterized in that: The temperature used to dissolve cellulose fibers in step (1) is 90-110℃.

5. The method for preparing conductive hollow cellulose fiber according to claim 1, characterized in that: The cellulose fiber concentration in the cellulose fiber solution obtained in step (1) is 10%-13%.

6. The method for preparing conductive hollow cellulose fiber according to claim 1, characterized in that: In step (2), hollow cellulose fibers are specifically produced by dry-wet spinning of cellulose fiber solution under pressure of 0.5 MPa and temperature of 110 °C using a coaxial spinneret.

7. The method for preparing conductive hollow cellulose fiber according to claim 1, characterized in that: The mass ratio of hollow cellulose fiber to trialdehyde phloroglucinol / acetic acid / dichloromethane mixture used in step (3) is 1:400, wherein the mass ratio of hollow cellulose fiber to trialdehyde phloroglucinol and acetic acid is 1:1:

10.

8. A conductive hollow cellulose fiber prepared by any one of claims 1-7.

Images