Rational macromolecular design and strategies to tune the microporosity for high-performance O2/N2 separation membranes

This review summarizes the performance of recently developed microporous polymers for practical industrial O2/N2 separations. The macromolecular design of innovative polymers of intrinsic porosity and derivatives is evaluated from the perspective of pore structure regulation for their outstanding O2/N2 separation performance. The structural groups that could fine-tune the free volume elements are examined to discern the promising moiety and architectures to improve size-based sieving. The long-term aging behaviors of the state-of-the-art macromolecules are also screened to explore the impacts of improved pore/free volume configuration. The strategies using thermal treatments to reset the structure of microporosity are inspected for their potential to improve the gas permeability or enhance size-specific molecular sieving, including the thermal rearrangement of polymeric membranes and pyrolyzed carbon molecular membranes using pre-crosslinked precursors and PIM-derived precursors. Membrane process design and optimization are summarized to evaluate the prospects of these novel membrane materials for large-scale industrial applications.