It might be due to the gas entrapment in the dope solution during the dissolution!

After dissolving the polymer in the solvent, let it stay still for at least 6 h. The bubbles formed during the mixing of the mixture will release.

Hi,

Keep your solution overnight after complete dissolution of polymer into solvent. I

Dear all,

at any stage if you can apply vaccum (in an oven for exemple) you will eliminate theses entrapped air bubbles. Regards

THF is very volatile. The best method is to let it stand. Time depends on your solution. Applying vacuum may lead to the loss of THF and lamination of the solution. If possible, I suggest that you use non-volatile solvent and use THF as co-solvent.

Good luck.

Hi Charif,

Yes the advice did help! Leaving a polymer to dissolve on its own overnight seems to be the best. I didn't end up using vacuum because like Xiang Li mentioned, vacuum would dry off the THF used to dissolve my polymer.

Lots of trial and errors involved, but hope this helps :)

Dear all,

Thank you for all your advice, I have been able to produce much better bubble-free membranes :) Appreciate it!