Membranes from polysulfone/N,N-dimethylacetamide/water system; Structure and water flux

Polymeric membranes were prepared by the wet-phase separation method from s olutions of different contents of polysulfone in N,N-dimethylacetamide; sol utions were cast in different thickness before immersion into the pure wate r coagulation bath. Two main processes take place during the formation of m embranes: nucleation and growth of the polymer lean phase with subsequent s olidification of the polymer rich phase, and the formation of channels, mac rovoids and mega-macrovoids. By the first process a cellular structure is f ormed whilst the second process connects the cells by opening the space bet ween them. The degree of interconnectedness is an additional factor that af fects the pure water flux. By changing the cast solution compositions and/o r their cast thickness the interconnectedness of the cells can be controlle d.