Highly Permeable Polybenzoxazole-Polyimide Copolymer Membranes for Gas Separation

Abstract

Development of polymeric materials with thermal, chemical and mechanical stabilities as well as high permeation characteristics has been required for large-scale applications containing CO2 separation. Recently, glassy polymers like PTMSP, PIMs and fluorinated polymers AF2400 have been focused due to their extraordinary gas permeation properties. However, these polymers showed low gas selectivity with physical aging problem during short-term operation. In this research, copolymer was successfully prepared from high permeable polybenzoxazole(PBO) derived from polyimide containing hydroxyl group via thermal rearrangement and highly selective polyimide(PI) having high thermal, chemical stabilities. Thermal rearrangement was confirmed by TGA-MS, ATR-IR, EA, etc. Furthermore, microporous characteristics were investigated by several analysis techniques such as wide angle X-ray diffraction, BET sorption isotherms, FFV calculated from density measurements. Gas permeation properties were characterized for small gas molecules according to the composition of PBO and PI domains. These novel copolymers showed advanced gas permeation and separation performances suitable for the commercial requirements of industrial applications.