Poly(ether imide sulfone) Membranes from Solutions in Ionic Liquids

Abstract

A membrane manufacture method based on nonvolatile solvents and a high-performance polymer, poly(ether imide sulfone) (EXTEM), is proposed as a greener alternative to the current industrial process. We dissolved EXTEM in pure ionic liquids: 1-ethyl-3-methylimidalzolium thiocyanate ([EMIM]SCN), 1-butyl-3-methylimidalzolium thiocyanate ([BMIM]SCN), and 1-ethyl-3-methylimidalzolium acetate ([EMIM]OAc). The following polymer solution parameters were evaluated to optimize the manufacture: Gibbs free energy of mixing (ΔG), intrinsic viscosity ([η]), and hydrodynamic diameter. Membranes with a sponge-like structure and narrow pore size distribution were obtained from solutions in [EMIM]SCN. They were tested for separation of proteins and DNAs (DNA). Due to the polymer stability, we foresee that applications in more demanding chemical separations would be possible. [EMIM]SCN was 96% purified and recovered after the membrane fabrication, contributing to the sustainability of the whole manufacturing process.