Mechanically and Thermally Enhanced Intrinsically Dopable Polyimide Membrane with Advanced Gas Separation Capabilities

In this paper, we present the first preparation of an intrinsically dopable polyimide (DPI) membrane containing an amine-capped aniline trimer (ACAT) that reveals advanced gas separation capabilities as well as mechanically and thermally enhanced properties. The as-prepared DPI membrane was synthesized by reacting ACAT and 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride) (BSAA) through a conventional thermal imidization reaction. Polyaniline (PANI) and conventional nondopable polyimide (NDPI) membranes were also prepared as controls. The DPI membranes were found to reveal permselectivities (a) of O-2/N-2 of about 13.54, which is about 1.96- and 1.54-fold higher than that of NDPI and PANI, respectively, based on the investigation of gas permeability analysis (GPA). Upon doping with 1.0 M HCl (aq), the pemselectivities of DPI for O-2/N-2 were found to be further increased to about 16.63. Moreover, significantly enhanced mechanical and thermal properties of the as-prepared DPI membrane were also found as compared to those of NDPI and PANI membranes, based on the studies of dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively.