Microporous polymers (pore size &lt; 2 nm) with well-defined free volume architecture are highly attractive materials for many applications such as gas separation membranes, gas storage media, and super absorbents, due to their good processability for mass production as well as high microporosity allowing for high performance. Recent research efforts on microporous polymers have been largely focused on (1) finely tuning the microcavity architecture (size and size distribution) to maximize separation performance and/or storage capacity, and (2) exploring new macromolecular designs to produce super rigid microporous structures that are resistant to physical aging. This talk will present a new class of microporous polyarylenes with heterocylic rings prepared from shape-persistent iptycene-based building blocks that are highly attractive for gas separation membranes and absorbents. Iptycenes (e.g., triptycene and pentiptycene), when incorporated into polymer backbone, are instrumental in generating large fractional free volume via disrupting chain packing. More importantly, the intrinsic internal microcavity defined by the molecular configurations of iptycene units offers unique opportunity to exquisitely tailor microporous architecture in iptycene-polymers. These unique structural features have led to microporous membranes with superior size sieving properties and ultrahigh permeabilities. The prepared iptycene-based polymers display among the highest selectivities for H2 separations (i.e., α(H2/N2) = 96; α(H2/CH4) = 203) and natural gas purification (i.e., α(CO2/CH4) = 68) among existing glassy polymers along with ultrahigh gas permeabilities. Their overall performance lies well beyond the 2008 permeability-selectivity upper bounds and several polymers even exceed the 2015 upper bounds defined by several ladder-type polymers. Notably, iptycene-containing microporous polymers showed excellent resistance toward membrane plasticization (under mixed-gas conditions) and physical aging due to intrinsic nature of the microporosity. Discussions will emphasize on elucidating fundamental relationships between microporous architecture and transport properties for these innovative iptycene-polymers to provide insight to guide new microporous polymer materials design.

Tailoring microporosity of iptycene-based polymers for separation membranes and beyond

256th National Meeting (2018)

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