Polymers are an attractive platform of materials for membrane-based separations needed to recover valuable resources. In this work, two new families of polymers are discussed for their application as gas separation membranes, one based on the Ring-Opening Metathesis Polymerization (ROMP)1, and one on Catalytic Arene-Norbornene Annulation (CANAL)2 polymerization. The high-molecular-weight polymers prepared via these routes are alternatives to traditional single-stranded polymers and offer a greater synthetic tunability. Figure 1 reports two generic structures for ROMPs (a) and CANALs (b). ROMPs are bottlebrush polymers that feature flexible backbones connecting pre-designed rigid ladder side-chains that form ultramicropores of different size. The CO2 permeability of CF3-ROMP (R=CF3) was measured to be &gt; 21,000 Barrer, which makes it the third most permeable polymer in literature. Furthermore, their resistance to CO2-induced plasticization is revealed to be the highest among uncrosslinked polymers to date. CANALs are rigid ladder polymers similar in structure to PIMs, but they feature norbornyl benzocyclobutene backbones, thereby introducing a third typology of ladder polymers to the gas separation field. Their unique purely hydrocarbon and nonpolar backbone make CANALs an exceptional model system for fundamental investigations of the structure-property relationships of ladder polymers. In both families of these new polymers, subtle changes in the substituents (i.e., R, R1, R2) have a tremendous impact on transport properties. The structural diversity explored in this work will serve to rationally design new microporous polymers with enhanced transport properties and stability, addressing fundamental limitations in current design strategies for polymer membranes.

ROMPs and CANALs: New approaches to design microporous polymers for gas separations

2019 Fall National Meeting

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