First choice isn't correct since when you mix solutions, the final concetrations will change.

Second choice also isn't correct, when you prepare a solution, then you add another compound, it may affect the final volume of solution.

Third choice is more resonable, you weigh appropriate quantities then you add the solvent to them.

Make sure that the final volume includes PAN AND GELATIN AND THE SOLVENT.

Dear Amilen cortês, the answer of Michel Rahal is Logical. Still, some so many different experts research in electrospinning field that they are not chemist and they don't know the exact concept of concentration; therefore, we can't conclude from your text which solutions are accurate. I recommend you to search some similar article to make sure which choice is the true answer, best regards

Mahyar Saber Thank you very much for your advice! I found 4 papers describing the preparation of PAN/GEL blends (whereby they are all papers from the same group and they use the same terminology)

Paper1 (2018):

"PAN solutions were prepared with PAN concentrations of 7.5% and 16% in DMSO by stirring for two hours at room temperature. The used water-soluble polymers were dextran, gelatin, agarose, PEG, starch, casein, poloxamer and agar in different concentrations as shown in Table 1."

From table 1:

22.6% gelatin without PAN ,13.04% gelatin with 12%PAN, 6.89%gelatin with 16%PAN.

https://doi.org/10.3934/matersci.2018.2.190

Paper 2(2018):

"The spinning solution contained 16% PAN in DMSO and 9% gelatin"

https://doi.org/10.1155/2018/6131085

Paper3(2019):

"The PAN solutions were prepared with a PAN concentration of 16% in DMSO by two-hour stirring at room temperature. Gelatine was added in the concentrations of 5% and 10%; higher concentrations were not spinnable."

https://doi.org/10.14502/Tekstilec2019.62.78-88

Paper4(2020):

"For the spinning solutions, X-PAN was dissolved in DMSO by stirring for 2 h at room temperature. Some of the spinning solutions were blended with ZnO , casein and gelatin.

From table:

PAN(mass/g) =1.6 ; Gelatin(mass/g)= 0.1 ; Cassein (mass/g)=0.1 ; DMSO(mass/g)= 8.5

Overall masses of the spinning solutions always add up to 10 g"

https://doi.org/10.3934/bioeng.2020004

-->Any thoughs/advices about that? And would you still say that option c) is correct? For me, it is clear how they dissolved PAN, but then they "add gelatine" to it (not clear if already solved or not)

Assuming that "16wt% PAN and 9wt%GEL" refers to the final solution, I would prepare the solution for instance like that:

For a 100g final solution:

i)Dissolve 16g in 44.1g DMSO (by stirring at RT for 2h)

ii)Dissolve 9g in 30.9g DMSO (by stirring at RT for 2h)

iii)Mix both solutions together (by stirring at RT for 2h)

-->Does that sounds reasonable to you? (From the papers it is not clear for me how long they stirred for each single solution and for how long after blending the solutions or how much DMSO is required to solve gelatine or to solve PAN separately).

I would really appreaciate any thoughts on that.

Thank you!

You're welcome.

I have read the mentioned articles and their contents are confusing; and I agree with you on how to make the solutions, but I also suggest an easier way for it.

i)Dissolve 16g in 84g DMSO (by stirring at about 30'C for 2h(Until a clear solution is obtained)

ii)Dissolve 9g gelatin in the solution obtained from the previous step (by stirring at about 30'C Until a clear solution is obtained)

In the end, to get fine fibers, if this is your first time dealing with this machine, I strongly recommend that you get help from an experienced person to master the technique.

Mahyar Saber Thank you so much for taking time to help me! I'll try it this way tomorrow! So far, I have only used a needle-based electrospinning machine to electrospin PAN solved in DMF. Tomorrow I'll use the needleless Nanospider (as described in the papers) for the first time! (I'm so excited about it!) But there will be an experienced person helping me with that:)

Good luck with your test tomorrow. I’ll have my fingers crossed 🤞

Well, it didnt work:/ But there are many possible reasons for that i.e. I don't know which is molecular weight of the PAN was used in the paper. My PAN (MW=150'000) was really firm (and I even didn't add gelatine). The expert in my lab suggested to find the spinnable concentration of gelatine(i.e. 5%, 7.5%, 10% in DMSO) and PAN ( i.e. 9%, 11%, 13% in DMSO) first. And then afterwards try to find a spinnable blend of them. The solutions should be ready tomorrow. Then, I will spin again :)

Dear Amilen Cortês

I suggest you read these papers:

1. Maneuvering surface structures of polyvinylidene fluoride nanofibers by controlling solvent systems and polymer concentration. Textile Research Journal. 89 (12), 2406-2422, 2019. DOI: 10.1177/0040517518792748.

2. Controlling the secondary surface morphology of electrospun PVDF nanofibers by regulating the solvent and relative humidity. Nanoscale research letters. 13 (1), 285-295, 2018. DOI: 10.1186/s11671-018-2705-0.

Best Regards,

Dr. Bilal Maan Zaarour

For preparing a solution for electrospinning, one way you could appropriate the concentration in your polymeric blend is by measuring weight-by-weight (w/w). You mentioned PAN/gelatine in DMSO as your blend. For simplicity’s sake, say you would like to make a 100 g solution of this blend. For 16% PAN and 9% gelatine, you would need to place 16 grams of PAN polymer and 9 grams of gelatine out of the total 100 grams in a container. This would mean 16+9= 25 g of polymer and the remaining 75 grams should be allocated for the solvent (in this case DMSO). Place DMSO in the container, for proper mixing you will need to leave it a magnetic stirrer for some time until the polymers dissolve completely.

Also, side note, it may be better to fill the container with the solvent (DMSO) first and then the polymers to make sure the polymers do not stick to the bottom of the jar.