We have designed and developed a diverse series of high-performance (HP) ionenes, or polymers which contain ionic groups along the main chain rather than as pendants. These materials merge the functionality utilized in high-performance engineering polymers, structural features associated with leading gas separation media, and precisely spaced ionic segments. These ionenes incorporate imidazolium cations paired with fluorinated anions (i.e. Tf<sub>2</sub>N), which are produced from established synthetic methods that impart great control over repeat unit complexity, functional group sequence, charge density, and regiochemistry. Varied connectivity and sophisticated structural segments known for imparting free volume, such as spirobisindane and Tröger’s base moieties, have also been incorporated along the backbone to improve gas transport performance. These ionenes are robust, exhibiting good thermal and mechanical stability, but extremely tailorable based on the versatile synthetic approaches which allow for innumerable potential derivatives based on deliberate combination of assorted monomers and linkages. These polymeric materials exhibit self-assembly when filled with “free” imidazolium-based ionic liquids (IL), which contributes additional tunability as the IL serves as a non-covalent cross-link between the polymer chains. We are investigating the effects of adding functional, ionic small molecules into the polymeric matrix which alter intramolecular interactions and promote further structuring within the ionic framework. These HP-ionenes and IL composites are thoroughly characterized in order to develop structure-property relationships between the polymer properties and the structural and functional features, and in order to understand the coordination between polymer chains and dispersed ionic additives. The performance of these novel ionenes and composites is tested in diverse applications including gas separation membranes, fibers, coatings, and 3D printing materials.

Tailorable design and methodical synthesis of structurally and functionally tunable ionenes + ionic liquid composites for high-performance engineering applications

ACS Spring Meeting 2021

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