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CN-121988191-A - Preparation method and application of porous para-aramid nanofiber membrane

CN121988191ACN 121988191 ACN121988191 ACN 121988191ACN-121988191-A

Abstract

The invention discloses a preparation method and application of a porous para-aramid nanofiber membrane. The preparation method of the para-aramid nanofiber membrane comprises the steps of placing a substrate coated with an aramid nanofiber solution in an aprotic solvent to obtain an aramid nanofiber membrane containing the aprotic solvent, immersing the aramid nanofiber membrane containing the aprotic solvent in the aprotic solvent, and heating and drying after the aprotic solvent in the nanofiber membrane is replaced by the aprotic solvent to obtain the para-aramid nanofiber membrane. The para-aramid nanofiber membrane prepared by the preparation method of the para-aramid nanofiber membrane has the advantages of high adjustable porosity and pore structure, great application prospect in the fields of battery diaphragm and membrane separation and the like, and the preparation method is simple and suitable for large-scale industrial application.

Inventors

  • WANG SUQING
  • WANG SHUPEI

Assignees

  • 华南理工大学

Dates

Publication Date
20260508
Application Date
20260201

Claims (10)

  1. 1. The preparation method of the porous para-aramid nanofiber membrane is characterized by comprising the following steps of: mixing and stirring para-aramid fiber, dimethyl sulfoxide, potassium hydroxide and deionized water to obtain para-aramid nanofiber solution; step two, forming a film from the para-aramid nanofiber solution obtained in the step one; immersing the membrane obtained in the step two into an aprotic solvent to obtain an initial para-aramid nanofiber membrane; Immersing the initial para-aramid nanofiber membrane into a proton solvent for solvent exchange, and removing aprotic solvent and solute in the para-aramid nanofiber membrane; And fifthly, drying the para-aramid nanofiber membrane obtained in the step four to obtain the porous para-aramid nanofiber membrane.
  2. 2. The method for preparing the porous para-aramid nanofiber membrane according to claim 1, wherein the deionized water in the first step is 0% -5% of the dimethyl sulfoxide by mass.
  3. 3. The method for preparing a porous para-aramid nanofiber membrane according to claim 1, wherein the para-aramid nanofiber membrane obtained in the fifth step has a structure with opposite sides.
  4. 4. The method for preparing a porous para-aramid nanofiber membrane according to claim 1, wherein the aprotic solvent in the third step comprises one or more of dimethyl sulfoxide, acetone, ethyl acetate, N-dimethylformamide, dimethylacetamide, chloroform, and petroleum ether.
  5. 5. The method for preparing the porous para-aramid nanofiber membrane according to claim 1, wherein the time for immersing the membrane obtained in the second step in the aprotic solvent is 10-7200 s.
  6. 6. The method for preparing a porous para-aramid nanofiber membrane according to claim 1, wherein the proton solvent in the fourth step comprises one or more of water, methanol, ethanol, propanol, isopropanol and butanol, and the solvent exchange time in the fourth step is preferably 0.2-12 h.
  7. 7. The method for preparing the porous para-aramid nanofiber membrane according to claim 1, wherein the drying temperature in the fifth step is 100-200 ℃ and the drying time is 0-12 h.
  8. 8. The method for preparing the porous para-aramid nanofiber membrane according to claim 1, wherein the mass concentration of the para-aramid nanofiber solution in the step one is 0.5-3 wt%.
  9. 9. A porous para-aramid nanofiber membrane, characterized in that the membrane is obtained by the preparation method of the para-aramid nanofiber membrane according to any one of claims 1 to 8, wherein the porous para-aramid nanofiber membrane is provided with a first layer and a second layer with two opposite sides, the first layer and the second layer have different pore size distribution, preferably, the first layer has a pore size distribution of 20 to 200 nm, and the second layer has a pore size distribution of 40 to 800 nm.
  10. 10. Use of a porous para-aramid nanofiber membrane obtained by the preparation method according to any one of claims 1 to 8 or a porous para-aramid nanofiber membrane according to claim 9, characterized in that it is used for a battery separator.

Description

Preparation method and application of porous para-aramid nanofiber membrane Technical Field The invention relates to the technical field of materials, in particular to a preparation method and application of a porous para-aramid nanofiber membrane. Background Para-aramid nanofiber membrane is widely applied to the fields of new energy, membrane separation and the like due to excellent mechanical properties, outstanding thermal stability, good electrical insulation capability, high chemical resistance and flame retardance. However, because of the strong hydrogen bond network and high crystallinity of the para-aramid nanofiber, the porosity and the pore structure of the para-aramid nanofiber membrane are difficult to adjust, and the para-aramid nanofiber membrane with high porosity and adjustable pore structure is difficult to prepare in a simple manner. In the prior art, the pore diameter of the para-aramid nanofiber membrane is adjusted by CN113506950A, and the pore structure of the para-aramid nanofiber membrane is adjusted by adopting a pore-forming agent, but the adjustment of the pore is very limited. CN110373814a, adopts the electrostatic spinning mode to prepare porous para-aramid nanofiber membrane, but because of poor spinnability of para-aramid, it needs to add spinning aid and is limited by solvent volatility, para-aramid needs to be processed under low spinning speed (< 0.5 ml/h) and heating condition (> 35 ℃). Based on the above problems, the present inventors have proposed a method for controlling para-aramid nanofiber membranes by aprotic solvents. Disclosure of Invention Aiming at the problems, the invention provides a preparation method and application of a porous para-aramid nanofiber membrane for the first time, the para-aramid nanofiber membrane with a highly adjustable pore structure is successfully prepared by the method, and the preparation method is simple in process, is beneficial to continuous production, and has breakthrough significance for the preparation of the para-aramid nanofiber membrane. The technical scheme of the invention is as follows: in a first aspect, the present invention provides a method for preparing a porous para-aramid nanofiber membrane, the method comprising: mixing and stirring para-aramid fiber, dimethyl sulfoxide, potassium hydroxide and deionized water to obtain para-aramid nanofiber solution; Step two, forming a film from the para-aramid nanofiber solution in the step one; immersing the membrane obtained in the step two into an aprotic solvent to obtain an initial para-aramid nanofiber membrane; Immersing an initial para-aramid nanofiber membrane into a proton solvent for solvent exchange, removing aprotic solvent and solute in the para-aramid nanofiber membrane, and regulating and controlling the aperture of the initial para-aramid nanofiber membrane; And fifthly, drying the para-aramid nanofiber membrane obtained in the step four to obtain the porous para-aramid nanofiber membrane. In the second step, the para-aramid nanofiber solution in the first step is formed into a film, and the para-aramid nanofiber solution in the first step is coated on a substrate to obtain the film. Further, in the first step, the mass ratio of the potassium hydroxide to the para-aramid fiber is 1.5-2:1, preferably 1.5:1. Further, the mass concentration of the para-aramid nanofiber solution obtained in the first step is 0.5-3 wt%. Further, the dosage of the deionized water in the step one is 0% -5% of the mass of the dimethyl sulfoxide, and preferably 0.01% -5%. Further, the substrate in the second step is one of a polyethylene terephthalate plate, a glass plate, a polyvinyl chloride plate or a polytetrafluoroethylene plate. Further, the aprotic solvent in the third step comprises one or more of dimethyl sulfoxide, acetone, ethyl acetate, N-dimethylformamide, dimethylacetamide, chloroform and petroleum ether. Further, in the third step, the soaking time of the aprotic solvent is 10-7200 s. Further, the proton solvent in the fourth step comprises one or more of water, methanol, ethanol, propanol, isopropanol and butanol. Further, the replacement time of the proton solvent in the fourth step is 0-12 h, preferably 0.5-10h. Further, in the fifth step, the drying temperature is 50-200 ℃ and the drying time is 0.5-12 h. In a second aspect, the present invention provides a para-aramid nanofiber membrane prepared by the method of the first aspect. Further, the para-aramid nanofiber membrane has a height-adjustable pore structure, and particularly, the gap of the para-aramid nanofiber membrane can be regulated and controlled between 20 nm and 800 nm. Further, the pore size distribution in the para-aramid nanofiber membrane is 20-800 nm. Further, the porosity of the para-aramid nanofiber membrane is 50-90%. Further, the thickness of the para-aramid nanofiber is 10-40 mu m. In a third aspect, the invention also provides a para-aramid nanofiber membrane with a two-sided anisotropic struc