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

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 TR-SIPN 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.