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., PH<inf>2</inf> = 9980; PO<inf>2</inf> = 3290 Barrer) with moderate selectivity (e.g., PH<inf>2</inf>/PN<inf>2</inf> = 11.0; PO<inf>2</inf>/PN<inf>2</inf> = 3.6) so that its data lie over the 2008 Robeson upper bounds for the H<inf>2</inf>/N<inf>2</inf>, O<inf>2</inf>/N<inf>2</inf>, and H<inf>2</inf>/CH<inf>4</inf> gas pairs and on the upper bound for CO<inf>2</inf>/CH<inf>4</inf>. 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<inf>2</inf> = 1170 Barrer; PO<inf>2</inf>/PN<inf>2</inf> = 5.4).