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Electrospinning technology is an efficient and simple technology for preparing nanofibers. The spinning principle is: the charged polymer solution or melt is drawn and refined under the action of the high-voltage electric field, and the solvent evaporates and the fibers solidify, finally forming nanofibers and depositing on the receiving device. Electrospun nanofibers have the advantages of small fiber diameter, large specific surface area, and high porosity. They have broad application prospects in high-efficiency filtration, nano-catalysis, biomedicine, functional textiles and other fields.In this section, we provide a knowledge introduction to the entire basic process from spinning material selection, spinning methods, characterization processing to post-processing.
Electrospinning is basically the drafting of polymer fluid. Many different types of polymers can be used for electrospinning to prepare fibers. The material used for electrospinning depends on the target application, material spinnability, material cost, solvent safety and solvent cost etc.(1) Commonly used electrospinning polymers and solvents used:NumPolymer nameAbbreviationSolvent1PolyoxyethylenePEODeionized water2Polyvinyl alcoholPVADeionized water3PolyvinylpyrrolidonePVPDeionized water, Ethanol、DMF4Polyvinylidene fluoridePVDFDMF、DMAc、（DMF：Acetone=7:3）5PolyacrylonitrilePANDMF、DMAc6PolycaprolactonePCLTCM、DCM、（DCM：DMF=7:3）7Polylactic acidPLAHFIP、TCM、DCM、（DCM：DMF=7:3）8PolyethersulfonePESDMF、DMAc9PolyurethanePUDMF、DMAc10PolystyrenePSDMF、DMAc、TCM 、THF11PolyamidePAFormic acid、HFIP12Cellulose acetateCA（DMF：Acetone=1:2）（85% Acetone：15% Deionized water）13ChitosanCSTrifluoroacetic acid, Acetic acid aqueous solution14Silk fibroinSFHFIP、Formic acid、TFA15CollagencollagenHFIP、TFE(2) Common solvent parameters for electrospinning:NumSolventDensity (g/cm3)Dielectric constantBoiling point (℃)Saturated vapor pressure(kPa)1Water1.078.54~80.21002.34 (25℃)2Ethanol0.79824.5578.55.33 (19℃)3DMF0.94536.71532.7 (20℃)4HFIP1.59617.7558.2102 (20℃)5THF0.8897.66621.6 (20℃)6TFA1.53542.172.414 (25℃)7TFE1.38327.57852 (20℃)8DCM1.3258.94047 (25℃)9TCM1.4834.816226.2 (25℃)10Formic acid1.2258.5100.55.33 (24℃)11Acetic acid1.0486.151171.5 (20℃)12Acetone0.79020.75630.8 (25℃)(3) Electrospinning materials commonly used in different applications:a. Air filtration/water filtration: PVDF, PAN, PA, PES, PU, PLA, PS, etc.b. Biomedicine: PEO, PCL, PLGA, PLA, collagen, silk fibroin, hyaluronic acid, chitosan, chitin, etc.c Battery separator:. PI, PEI, PVDF, PMIA, etc.d. Waterproof and breathable: PU, PVDF, etc.e. Carbon nanofiber: PAN, PVP, etc.f. Inorganic nanofiber spinning aid materials: PVA, PVP, etc.g. Adsorption separation: CA, PAN, chitosan, etc. (4) Electrospinning commonly used receiving substrate:Aluminum foil paper, release paper, glossy paper, spunbond cloth, melt blown cloth, plastic screen, wood pulp fiber paper, etc.Read More
Take PVDF nanofiber membrane preparation as an example:1 Main materials and instruments:(1) Spinning material: PVDF, molecular weight 400,000; solvent DMF, analytically pure.(2) Experimental equipment: 50mL conical flask, water bath magnetic stirrer, electronic balance, E05 electrostatic spinning machine.2 Spinning solution configuration:Use an electronic balance to weigh a certain quality of solvent DMF into an Erlenmeyer flask, add a magnetic stirrer, and stir in a water bath; then weigh a certain quality of PVDF and slowly add it to the stirring Erlenmeyer flask; cap the bottle tightly to prevent Water vapor enters the Erlenmeyer flask; set the temperature of the water bath to 60°C, and continuously stir and dissolve for 4 hours until the solution is clear and transparent, and a PVDF spinning solution with a certain mass concentration can be obtained. According to this method, prepare 20g, 18%wt PVDF spinning solution.3 Spinning process and parametersPump the above PVDF spinning solution into a 20mL syringe, fix the syringe to the injection pump of the spinning machine, install a 20G (1/2 inch, flat mouth) stainless steel needle, connect the needle to the positive pole of the high-voltage power supply, and connect the receiving roller to the negative pole of the high-voltage power supply. The receiving substrate is pasted on the roller; the syringe pump specifications are set to 20mL, the liquid supply speed is 2mL/h, the roller speed is 300 rpm, the sliding table stroke is 20cm, the spinning distance is 15cm, and the spinning voltage is positive 15kV and negative 5kV. The temperature is 35℃, the humidity is 40%, and the timing is 120min. Finally, close the equipment door and open the exhaust air.Commonly used electrospinning receiving substrate: aluminum foil paper, release paper, non-woven fabric, mesh cloth, etc.Read More
Commonly used characterization methods in electrospinning experiments are:(1) Characterization of spinning solution characteristics: viscosity, surface tension, conductivity test(2) Composition characterization: infrared spectrum, Raman spectrum, ultraviolet-visible absorption spectrum, X-ray electronic energy spectrum, energy dispersive X-ray spectrum(3) Structural characterization: BET nitrogen adsorption method, X-ray diffraction(4) Morphology characterization: scanning electron microscope, transmission electron microscope, atomic force microscope, fluorescence microscope(5) Thermal characterization: thermogravimetric analysis, thermal differential analysis and differential scanning calorimetry(6) Mechanical characterization: tensile performance, compression performance(7) Electrical characterization: resistance and resistivity test, dielectric characteristic test(8) Characterization of filtration performance: filtration efficiency, resistance, and air permeability For more content updates, please continue to follow us.Read More