Materials-driven, membrane-based separation technologies have great promise to dramatically drive down the energy consumption, carbon footprint, and water intensity of traditional thermally-driven separation technologies, such as cryogenic distillation.  The creation of novel membrane materials with precisely controlled structures and properties holds the key to enabling low energy membrane-mediated solutions to many of the separation-related challenges facing humanity in environment, energy, and sustainability.  Microporous polymers, or high-free-volume polymers, are leading membrane materials for gas separations.  However, existing microporous polymer membranes that follow size-sieving mechanism suffer from permeability-selectivity tradeoff, physical aging (loss of permeability over time) and membrane plasticization (loss of size sieving capability upon sorption of condensable gases like CO<sub>2</sub>).  The molecular origin of these materials challenges largely lies in the transient nature of non-equilibrium conformational free volume dictated by polymer chain packing. To address these major challenges, we introduce a new concept of configurational free volume in the macromolecular design to mimic non-collapsible, permanent microcavities in inorganic molecular sieves, thus enabling physical aging and plasticization resistance in corresponding microporous polymer membranes.  This presentation will describe several novel strategies that introduce configuration-based free volume in microporous polymers.  Specifically, one major strategy is the incorporation of shape-persistent iptycene-based structure units in the polymer structure, which contain intrinsic molecular microcavities delineated by the molecular configuration of iptycene moieties.  The other strategy focuses on the construction of super rigid microporous polymer architecture exploiting crosslinked model network structures.  The introduction of configurational free volume in microporous polymers has led to exciting separation performance surpassing the upper bounds as well as excellent resistance toward physical aging and plasticization.  This talk will emphasize on new macromolecular design concepts and the understanding of fundamental structure-property relationships for this new class of microporous polymer membrane materials.

Microporous polymers with engineered configurational free volume microporosity for gas separation membranes

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.