Hi, I am working on PBI membranes for FC applications. I have prepared a PBI polymer using the monomers 3,3-diaminobenzidine and isophthalic acid. When I try to cast it as a membrane the polymer is not miscible with DMAc solvent a powder-like material settles down, so I tried centrifuging it filtered the solution and cast the clear solution even the membrane was not formed. Can someone help me in this regard
Dear Siva Moorthy, please specify the type of the membrane (filtration, electrochemical celles, ...). Please have a look at the attached file. My Regards
Add a little amount of lithium chloride to the DMAC and solubilize PBI at hot conditions.
Dear Siva,
DMAc is perfect for dissolving PBI. However, it has very low solubility limits at normal room temperature and pressure. I suggest you use the pyrex bottle with cap sustainable for high temperature and put it for dissolution at a temperature about 120~150 deg. centigrade.
For casting, you may try initially in glass Petri dishes and scale-up using the doctor blade technique.
In order to increase the shelf life of your PBI/DMAc solution, add 5 wt% of lithium chloride to the solution.
Good luck!
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