Microporous Polysulfones with Enhanced Separation Performance via Integration of the Triptycene Moiety

Abstract

Here, we report the synthesis of two polysulfones containing either triptycene or phenolphthalein as the bulky bridging unit in the polymer backbone to investigate the influence of the rigid, unwieldy structures on chain rigidity, fractional free volume, and gas transport properties. Incorporation of the triptycene unit provided the most rigid backbone, greatest fractional free volume, and strongest gas separation performance, because of its exceptional combinations of permeability and selectivity, relative to many commercial polymers and other polysulfones reported in the literature. In addition, integration of the triptycene unit and its intrinsic, configuration-based free volume provided good resistance to physical aging. In particular, the triptycene-based polysulfone experienced exceptional H2/CH4 selectivity (156) combined with nearly doubled H2 permeability, as well as promising O2/N2 separation performance with an O2 permeability of 1.5 Barrer, which is an ∼21% increase, relative to that of the bisphenol A-based commercial polysulfone, to go along with an O2/N2 selectivity of 7.7.