You have the problem of early solidification of the solution. There may be different reasons for this. Can you answer the following questions to better analyze the problem?

1. How did you prepare the solution? Did you rise to high temperatures while dissolving the polymer?

2. What is the molecular weight of your polymer? Have you tried 11-12% concentration?

3. Have you tried this solution on needle electrospinning?

4. Have you experienced the same problem with a different polymer in needleless electrspinning?

5. What type of needleless system do you use? cylinder, disc, wire etc.

6. What is your TCD value? Have you reached higher values?

My guess it is related to high extrusion rate or high polymer concentration.

Behzat YILDIRIM

I used magnetic stirrer at 400 rpm and temperature 50 C

PAN Mw=150,000

Yes I tried from 8wt% to 12wt% but at all solution there are hanging nanofibers which are not deposited on the aluminum foil, and these nanofibers are not dried but have drops of solvent and are wet. Even I changed distance from 125 mm to 240mm.

I don't have needle electrospinning here

No with DMF solvent, PAN has very good deposited nanofibers and there is no electrospraying on same parameters

I am using wire system

Nozzel size I used 0.6, 0.7 & 0.8mm

This is probably due to the lower evaporation rate of DMSO compared to DMF. You could try using a heat lamp to accelerate evaporation. You could also try moving your target foil further away, as 240mm is not very far, but I'm assuming there are geometric constraints. You might also consider adding a more volatile co-solvent although that may complicate the issue considerably.

Hi Muhammad Hassan Rafe,

I ask these questions for the following reasons.

1. If the polymer is dissolved at high temperature, the molecular structure may be degraded. This means that the molecular chains are broken.

2. It is natural to see this problem if the concentration of the solution is high.

3. You have had no problems with the needle electrospinning with the solution. This means that there is a problem with the device. If it is positive, the first two questions are not needed.

4. If you tried a different polymer and succeeded, it means that there is a problem with the solution.

5. This problem may occur if you are using a circular feed system. You can try smaller diameters.

6. At very low TCD values, the solvent cannot find time to evaporate due to shorter flight time, which may cause early solidification.

According to your answers, there is no solution-related problem. In the PAN polymer, DMF is a better solvent than DMSO, but I'm not sure that this is the source of the problem. DMF can be tried if possible.

In the image, the nanofiber solidifies on the wire at close range. But I think the collector starts solidifying first, then accumulates down to the wire. Is this true? The problem seems to be related to environmental conditions or device parameters.

1. Use a larger diameter wire if possible.

2. Increase the movement speed of the head on the wire

3. Use a lamp that acts as a heater as Britannia Vondrasek suggests.

4. Run the vent continuously to remove the evaporated solvent.

5. Make sure that the ambient temperature and huminity does not change.

6. Determine the relationship between the applied voltage and the TCD. Do not apply too low or too high voltage, you should work at the optimum value.

7. It may have a low effect but try at a solution temperature of 65-70°C.