Preparation and Gas Separation Properties of Polyimide Membranes Containing Polyether Segments

A series of polyimide membranes containing polyether amine (PPO) segment were successfully synthsized by thermal imidization of the poly(amic acid) (PAA) precursors copolymerized of pyromellitic dianhydride (PMDA) with 4, 4'-diaminodiphenyl ether (ODA) and amine functionalized polyether amine (M-n similar to 2000). The effects of PPO on the microstructure and gas separation property of the resultant membranes were investigated in detail. The results show that the fractional free volume (FFV) of the membranes increases with the content of the PPO. Meanwhile, a micro-phase separation behavior is detected in the resultant membranes with the incorparation of PPO, which can act as the continuous gas transmission channel. As a consequence, the permeability of the membrane increases rapiadly. As the PPO content reaches 65 wt%, the CO2 permeability is as high as 131.61 Barrer, which is nearly 22 times higher than that of the PMDA/ODA homopolyimide membrane. Moreover, due to the special interaction between the PPO and CO2, the CO2/N-2 selectivity increases from 18.77 for the PMDA/ODA membrane to 30.12 for the copolyimide membrane with 65 wt% PPO. Accordingly, the incorporation of PPO plays an important role in modifying the microstructure and gas separation property for the polyimide membranes. [GRAPHICS] .