Dear researchers,
I fabricate the UF PVDF membranes by phase inversion method (NIPS); therefore, they are water- wet membranes. Then I immerse them in aqueous alcohol solution. What is the reason of replacing the alcohol molecules with water molecules in the pores?
Regards
We use isopropanol, but the concept is the same. Think of it as putting a monolayer of alcohol on the surface of the membrane. The hydrophobic portion of the alcohol interacts with the membrane, orienting the polar OH groups outward. This creates a polar surface that helps wick water into the small pores. Once wetted we rinse the filter for several minutes to displace the alcohol to avoid contamination. Losing the alcohol layer is not a problem though because the small pores are already filled with water.
Usually the membranes prepared immersing in the final water bath for a period of 2-3 days, with daily change of water, so as to ensure thorough removal of residual solvent and additives prior to final membrane drying.So I suppose that you are used alcohol instead of water this is depending on the type of solvent that used in the membranes preparation.
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