The enhancement of chain rigidity and gas transport performance of polymers of intrinsic microporosity via intramolecular locking of the spiro-carbon

Here, we present a new strategy to improve the rigidity of PIM-1 through the introduction of 8-membered ring locking into the flexible spiro-carbon pivot point to produce an interlocked polycyclic structure. This locked version of PIM-1 shows simultaneous increases in both permeability and selectivity that place it well above the Robeson upper bound for a number of important gas pairs. Molecular modelling demonstrates that the locked version of PIM-1 is much more rigid.