Polyimide composite nanofiber membrane with sandwich structure and preparation method thereof

[0032] Example 1

[0033] 1) Dissolve 20 g of polyimide acid in 20 g of DMAC solution, heat and stir at 80° C. for 30 min, until completely mixed uniformly, to obtain polyimide acid spinning solution. Take 0.6g polytetrafluoroethylene micro-nano powder, 0.6g polyvinylidene fluoride micro-powder, 4.4g DMF, 4.4g acetone, first mix DMF and acetone evenly, then add polytetrafluoroethylene micro-nano powder and polyvinylidene fluoride in turn Finely powdered, stirred at room temperature for 3 hours, and thoroughly mixed to obtain a polytetrafluoroethylene-polyvinylidene fluoride spinning solution.

[0034] 2) Using an electrospinning device, first spin 4mL polyimide acid solution to make an electrospun membrane, and then directly electrospin 4mL polytetrafluoroethylene-polyvinylidene fluoride mixed solution on the polyimide electrospun membrane Finally, 4 mL of polyimide acid solution was spun into an electrospun membrane to obtain a composite membrane with a sandwich structure. Among them, the spinning parameters adopted in the electrospinning process of polyimide acid electrospinning solution are: the voltage is 15KV, the distance between the spinneret and the receiving substrate is 10cm, and the feeding speed is 1mL/h. The spinning parameters used in the electrospinning process of polytetrafluoroethylene-polyvinylidene fluoride mixed electrospinning liquid are: the voltage is 12KV, the distance between the spinneret and the receiving substrate is 12cm, and the feeding speed is 1mL/h.

[0035] 3) Smooth the sandwich structure film and put it into an oven for thermal imidization. Set up the oven operation program, firstly raise the oven temperature to 350°C within 30 minutes for preliminary imidization, then keep it at 350°C for 15 minutes to further convert polyimide acid into polyimide, and finally cool to room temperature to obtain polyimide Imide/PVDF-PTFE/Polyimide sandwich film.

[0036] Dielectric performance test: Novocontrol CONCEPT 80 broadband dielectric impedance spectrometer was used to test the dielectric constant and dielectric loss of the obtained film. The room temperature is 25°C, and the frequency range is controlled at 10-10 7 Hz.

[0037]Example 2

[0038] 1) Dissolve 20 g of polyimide acid in 20 g of DMAC solution, heat and stir at 80° C. for 30 min, until completely mixed uniformly, to obtain polyimide acid spinning solution. Take 0.6g polytetrafluoroethylene micro-nano powder, 0.6g polyvinylidene fluoride micro-powder, 4.4g DMF, 4.4g acetone, first mix DMF and acetone evenly, then add polytetrafluoroethylene micro-nano powder and polyvinylidene fluoride in turn Finely powdered, stirred at room temperature for 3 hours, and thoroughly mixed to obtain a polytetrafluoroethylene-polyvinylidene fluoride spinning solution.

[0039] 2) Using an electrospinning device, first spin 4mL polyimide acid solution to make an electrospun membrane, and then directly electrospin 2mL polytetrafluoroethylene-polyvinylidene fluoride mixed solution on the polyimide electrospun membrane Finally, 4 mL of polyimide acid solution was spun into an electrospun membrane to obtain a composite membrane with a sandwich structure. Among them, the spinning parameters adopted in the electrospinning process of polyimide acid electrospinning solution are: the voltage is 15KV, the distance between the spinneret and the receiving substrate is 10cm, and the feeding speed is 1mL/h. The spinning parameters used in the electrospinning process of polytetrafluoroethylene-polyvinylidene fluoride mixed electrospinning liquid are: the voltage is 12KV, the distance between the spinneret and the receiving substrate is 12cm, and the feeding speed is 1mL/h.

[0040] 3) Smooth the sandwich structure film and put it into an oven for thermal imidization. Set up the oven operation program, firstly raise the oven temperature to 350°C within 30 minutes for preliminary imidization, then keep it at 350°C for 15 minutes to further convert polyimide acid into polyimide, and finally cool to room temperature to obtain polyimide Imide/PVDF-PTFE/Polyimide sandwich film.

[0041] Dielectric performance test: Novocontrol CONCEPT 80 broadband dielectric impedance spectrometer was used to test the dielectric constant and dielectric loss of the obtained film. The room temperature is 25°C, and the frequency range is controlled at 10-10 7 Hz.

[0042] Example 3

[0043] 1) Dissolve 20 g of polyimide acid in 20 g of DMAC solution, heat and stir at 80° C. for 30 min, until completely mixed uniformly, to obtain polyimide acid spinning solution. Take 0.6g polytetrafluoroethylene micro-nano powder, 0.6g polyvinylidene fluoride micro-powder, 4.4g DMF, 4.4g acetone, first mix DMF and acetone evenly, then add polytetrafluoroethylene micro-nano powder and polyvinylidene fluoride in turn Finely powdered, stirred at room temperature for 3 hours, and thoroughly mixed to obtain a polytetrafluoroethylene-polyvinylidene fluoride spinning solution.

[0044] 2) Using an electrospinning device, first spin 4mL polyimide acid solution to make an electrospun membrane, and then directly electrospin 8mL polytetrafluoroethylene-polyvinylidene fluoride mixed solution on the polyimide electrospun membrane Finally, 4 mL of polyimide acid solution was spun into an electrospun membrane to obtain a composite membrane with a sandwich structure. Among them, the spinning parameters adopted in the electrospinning process of polyimide acid electrospinning solution are: the voltage is 15KV, the distance between the spinneret and the receiving substrate is 10cm, and the feeding speed is 1mL/h. The spinning parameters used in the electrospinning process of polytetrafluoroethylene-polyvinylidene fluoride mixed electrospinning liquid are: the voltage is 12KV, the distance between the spinneret and the receiving substrate is 12cm, and the feeding speed is 1mL/h.

[0045] 3) Smooth the sandwich structure film and put it into an oven for thermal imidization. Set up the oven operation program, firstly raise the oven temperature to 350°C within 30 minutes for preliminary imidization, then keep it at 350°C for 15 minutes to further convert polyimide acid into polyimide, and finally cool to room temperature to obtain polyimide Imide/PVDF-PTFE/Polyimide sandwich film.

[0046] Dielectric performance test: Novocontrol CONCEPT 80 broadband dielectric impedance spectrometer was used to test the dielectric constant and dielectric loss of the obtained film. The room temperature is 25°C, and the frequency range is controlled at 10-10 7 Hz.