Novel poly(ether sulfone) with tetraphenyl bipyrimidine unit for gas separation

Abstract Poly (ether sulfone) (PES), as a kind of special engineering plastic, is widely used in the field of separation. However, its gas separation performance is unremarkable. Therefore, a series of PES containing the tetraphenyl bipyrimidine unit (PES-TPhbpy-x) was prepared by nucleophilic polycondensation to improve the gas separation performance of PES. PES-TPhbpy-x exhibited a high molecular weight, excellent mechanical properties, and could form robust membranes. With increasing TPhbpy unit content in PES-TPhbpy-x, the glass transition temperature and heat resistance increased. WAXD analysis revealed that the d-spacing of PES-TPhbpy-x is larger than that of PES. This indicated that the TPhbpy unit could hinder the polymer chain packing and enhance the rigidness of the polymers. Compared with PES, PES-TPhbpy-x exhibited an excellent gas separation performance. The CO2 permeability of the PES-TPhbpy-100 increased by 570%, and the CO2/N2 selectivity and CO2/CH4 selectivity increased by 49% and 50%, respectively. Moreover, PES-TPhbpy-100 could form a membrane by the hot-press method. The CO2 permeability of the PES-TPhbpy-100 membrane prepared by the hot-press method was 12.81 barrer. In addition, the CO2/N2 and CO2/CH4 selectivities were 32.0 and 37.7, which were 27% and 35% higher than those of the PES membrane, respectively.