Preparation of poly(ether sulfone) and poly(ether imide) hollow fiber membranes for gas separation: Effect of internal coagulant

Abstract

The internal coagulant plays a very important role in the preparation of hollow fiber membranes. In this paper, the influence of the internal coagulant on hollow fiber formation, structures, and gas separation performance of polyethersulfone (PESf) and polyetherimide (PEI) membranes are presented. The internal coagulants used include water, methanol, ethanol, 2-propanol, and mixtures of the alcohols and water. Water was always used as the external coagulant. Polymer dopes containing a polymer and a solvent mixture of N-methyl-2-pyrrolidone (NMP) and ethanol (EtOH) were formulated to give low coagulation values. The correlation of coagulant properties with gas permeation properties, membrane structure, and membrane integrity is addressed.