Microporous polymers of extreme rigidity are required for gas-separation membranes that combine high permeability with selectivity. We report a shape-persistent ladder polymer consisting of benzene rings fused together by inflexible bridged bicyclic units. The polymer's contorted shape ensures both microporosity-with an internal surface area greater than 1000 square meters per gram-and solubility so that it is readily cast from solution into robust films. These films demonstrate exceptional performance as molecular sieves with high gas permeabilities and good selectivities for smaller gas molecules, such as hydrogen and oxygen, over larger molecules, such as nitrogen and methane. Hence, this polymer has excellent potential for making membranes suitable for large-scale gas separations of commercial and environmental relevance.

Ultrapermeable benzotriptycene-based PIMs show exceptional gas selectivities that define new positions for the CO2/CH4 and CO2/N2 Robeson upper bounds.

A highly gas permeable polymer with exceptional size selectivity is prepared by fusing triptycene units together via a poly­merization reaction involving Tröger's base formation. The extreme rigidity of this polymer of intrinsic microporosity (PIM‐Trip‐TB) facilitates gas permeability data that lie well above the benchmark 2008 Robeson upper bounds for the important O2/N2 and H2/N2 gas pairs.

A highly gas-permeable polymer with enhanced selectivities is prepared using spirobifluorene as the main structural unit. The greater rigidity of this polymer of intrinsic microporosity (PIM-SBF) facilitates gas permeability data that lie above the 2008 Robeson upper bound, which is the universal performance indicator for polymer gas separation membranes.

The promise of ultrapermeable polymers, such as poly(trimethylsilylpropyne) (PTMSP), for reducing the size and increasing the efficiency of membranes for gas separations remains unfulfilled due to their poor selectivity. We report an ultrapermeable polymer of intrinsic microporosity (PIM-TMN-Trip) that is substantially more selective than PTMSP. From molecular simulations and experimental measurement we find that the inefficient packing of the two-dimensional (2D) chains of PIM-TMN-Trip generates a high concentration of both small (<0.7 nm) and large (0.7-1.0 nm) micropores, the former enhancing selectivity and the latter permeability. Gas permeability data for PIM-TMN-Trip surpass the 2008 Robeson upper bounds for O/N, H/N, CO/N, H/CH and CO/CH, with the potential for biogas purification and carbon capture demonstrated for relevant gas mixtures. Comparisons between PIM-TMN-Trip and structurally similar polymers with three-dimensional (3D) contorted chains confirm that its additional intrinsic microporosity is generated from the awkward packing of its 2D polymer chains in a 3D amorphous solid. This strategy of shape-directed packing of chains of microporous polymers may be applied to other rigid polymers for gas separations.

Introducing the highly rigid ethanoanthracene unit into polyimides of intrinsic microporosity provides an impressive enhancement of gas selectivity by molecular sieving.

The development of polymeric anion-exchange membranes (AEMs) combining high ion conductivity and long-term stability is a major challenge for materials chemistry. AEMs with regularly distributed fixed cationic groups, based on the formation of microporous polymers containing the V-shape rigid Tröger's base units, are reported for the first time. Despite their simple preparation, which involves only two synthetic steps using commercially available precursors, the polymers provide AEMs with exceptional hydroxide conductivity at relatively low ion-exchange capacity, as well as a high swelling resistance and chemical stability. An unprecedented hydroxide conductivity of 164.4 mS cm(-1) is obtained at a relatively a low ion-exchange capacity of 0.82 mmol g(-1) under optimal operating conditions. The exceptional anion conductivity appears related to the intrinsic microporosity of the charged polymer matrix, which facilitates rapid anion transport.

A novel polymer of intrinsic microporosity (PIM) was prepared from a diaminobenzotriptycene monomer using a polymerization reaction based on Troger's base formation. The polymer (PIM-BTrip-TB) demonstrated an apparent Brunauer, Emmet, and Teller (BET) surface area of 870 m 2 g −1 , good solubility in chloroform, excellent molecular mass, high inherent viscosity and provided robust thin films for gas permeability measurements. The polymer is highly permeable (e.g., PH 2 = 9980; PO 2 = 3290 Barrer) with moderate selectivity (e.g., PH 2 /PN 2 = 11.0; PO 2 /PN 2 = 3.6) so that its data lie over the 2008 Robeson upper bounds for the H 2 /N 2 , O 2 /N 2 , and H 2 /CH 4 gas pairs and on the upper bound for CO 2 /CH 4 . On aging, the polymer demonstrates a drop in permeability, which is typical for ultrapermeable polymers, but with a significant increase in gas selectivities (e.g., PO 2 = 1170 Barrer; PO 2 /PN 2 = 5.4).