Intrinsically Microporous Soluble Polyimides Incorporating\nTroger’s Base for Membrane Gas Separation

Abstract

Polyimides\nwith intrinsic microporosity were readily prepared by\nintroducing Tröger’s base (TB) into the polymer backbone\nvia polymerization between imide-containing diamines and dimethoxymethane\n(DMM). Two imide-containing diamines were prepared by reaction of\n2,5-dimethyl-1,4-phenylenediamine (DPD) with 4,4′-(hexafluoroisopropylidene)­diphthalic\nanhydride (6FDA) and 3,3′,4,4′-benzophenonetetracarboxylic\ndianhydride (BTDA). The resulting polyimides were readily soluble\nin common organic solvents, had good mechanical properties, with tensile\nstrength in the range of 59–64 MPa and elongation at break\nof 5–17%, good thermal stability and extremely high glass transition\ntemperatures (<i>T</i>_gs), up to 425 °C.\nThe polyimides with incorporated TB units had high fractional free\nvolume (FFV ≥ 0.215) resulting from poor chain-packing and\nexhibited significant microporosity and good gas transport properties.\nThe novel polymer architecture in this study extends the development\nof polyimides with intrinsic microporosity for membrane-based gas\nseparation.