Polyaniline/polyimide blends for pervaporation and gas separation studies

Free-standing fully dense films have been successfully produced from drying blends of polyaniline and a polyamic acid precursor to polyimide. These blends exhibit an improved thermal stability relative to polyaniline. In gas permeability studies, a polyaniline/polyimide blend has a greater gas selectivity and shows an increase in permeability for all gases studied relative to polyimide. Pervaporation of water and water/acetic acid mixtures has been performed using these blends. The selectivity of the blends for water/acetic acid mixtures is considerably improved from that of undoped polyaniline and is comparable to that of HCl doped polyaniline. This is consistent with some of the polyamic acid acting as a “polymeric” dopant. The polymeric dopants also lead to lower fluxes for water/acetic acid relative to undoped polyaniline.