Pervaporation performance of polyetherimide membranes spin‐ and dip‐coated with polydimethylsiloxane

Abstract The pervaporation performance of polydimethylsiloxane (SR) spin‐ and dip‐coated polyetherimide (PEI) membranes was inmvestigated for acetic acid/water mixture. The spincoating technique was used to produce a thin, uniaform coating, and compared to the dipcoating technique in terms of pervaporation performance, thickness, and uniformity of the coatiing layer. It was fould that the PEI membranes studied were water‐selective and that the water selectivity of PEI membranes increased when spin‐coated with a SR solution. It wal also fould that the water selectivity increased when the PEI membranes were conated with SR solutions of increassing concentration, Althought the permeate flux noticeably decreased. The coating thickness was measured by the weighting techniquo and the results were compared with the thickless estimation by two versins of the resistance model. It was determined that the spin‐coating technique can provide a thinner and more uniform coating than the dip‐coating technique, and that the coating solution penetrates the mem brane pores beofre coating the surface. © 1994 John Wiley & Sons, Inc.