Highly Permeable Benzotriptycene-Based Polymer of Intrinsic Microporosity

A novel polymer of intrinsic microporosity (PIM) was prepared from a diaminobenzotriptycene monomer using a polymerization reaction based on Tröger’s base formation. The polymer (PIM-BTrip-TB) demonstrated an apparent Brunauer, Emmet, and Teller (BET) surface area of 870 m² 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., <i>P</i>H₂ = 9980; <i>P</i>O₂ = 3290 Barrer) with moderate selectivity (e.g., <i>P</i>H₂/<i>P</i>N₂ = 11.0; <i>P</i>O₂/<i>P</i>N₂ = 3.6) so that its data lie over the 2008 Robeson upper bounds for the H₂/N₂, O₂/N₂, and H₂/CH₄ gas pairs and on the upper bound for CO₂/CH₄. 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., <i>P</i>O₂ = 1170 Barrer; <i>P</i>O₂/<i>P</i>N₂ = 5.4)