Effect of solvent and cosolvent on the morphology and permeance of asymmetric polyimide membrane

Abstract

The effect of solvent/cosolvent composition on the morphology and permeance of polyimide membrane was investigated. Asymmetric membranes were fabricated through phase inversion using immersion-precipitation method. The mixture of gamma-butyrolactone (GBL) and N-methyl-2-pyrrolidinone (NMP) was used as solvent. The membrane morphology changed from finger-like to sponge-like as the proportion of GEL increased. It was proved that the heat of mixing of solvent and nonsolvent was an important factor in controlling the membrane morphology. Membranes of finger-free morphology and high permeance could be prepared by controlling the solvent/cosolvent ratio.