Effect of PEG additives on properties and morphologies of polyetherimide membranes prepared by phase inversion

Abstract

This study investigated the effect of poly(ethylene glycol) (PEG) additive as a pore-former on the structure formation of membranes and their permeation properties connected with the changes in thermodynamic and kinetic properties in the phase inversion process. The membranes were prepared by using polyetherimide/N-methyl-2-pyrrolidone/PEG (PEI/NMP/PEG) casting solution and water coagulant. The resulting membranes, prepared by changing the ratio of PEG to PEI, were characterized by scanning electron microscope (SEM) observations, measurements of water flux and γ-globin rejection. The thermodynamic and kinetic properties of the membrane-forming system were studied through viscosity. The pore radius distribution curves were especially obtained by differential scanning calorimetry (DSC). Furthermore, the membranes were characterized for pure water flux and rejection of solute and by SEM observation. The filtration results agreed well with the SEM observations. As expected, PEG with a fixed molecular weight (PEG 600) acted as a pore forming agent, and membrane porosity increased as the PEG content of the casting solution increased.