Thermally rearranged semi-interpenetrating polymer network (TR-SIPN) membranes for gas and olefin/paraffin separation

Abstract

Membrane-integrated gas separation is of great interest due to its energy-saving and economic merits. Although easy-to-process polymer membranes have shown potential, insufficient gas permeation and low stability in harsh environments limit their use in practical applications. Here, we demonstrate nanoporous and rigid semi interpenetrating polymer networks (SIPNs) by incorporating crosslinked network into polymer matrices, accompanying interpenetration and thermal rearrangement (TR) to construct an optimized microporous structure where nanometric and sub-nanometric pores coexist parallel to the gas transport direction. The resulting TRSIPN improves gas transport without sacrificing separation efficiency since the nanometric and sub-nanometric pores serve as molecular highways and selective bottlenecks, respectively. Furthermore, the plasticization resistance against condensable gases was enhanced due to improved polymer rigidity of the TR-SIPNs. Our study suggests wide applicability of polymer membranes for aggressive gas separations such as natural gas sweetening and olefin/paraffin separation.