Metal-containing ionic liquids (MCILs) combine the desirable properties of conventional organic ionic liquids (e.g., negligible vapor pressure, ionic conductivity, high solubility for certain light gases) with the unique properties afforded by having a metal center (e.g., metal-based magnetic, optical, catalytic, or molecular binding properties). Polymers prepared from MCIL monomers or containing MCIL repeat units have been shown to be processible, solid-state materials with many of the functional properties of MCILs. A relatively new, related area of research is the preparation of block copolymers (BCPs) based on MCILs. By combining the properties of poly(MCIL)s with the ability of BCPs to phase-separate into ordered microstructures, MCIL-based BCPs represent a new class of polymer materials in which differences in nanostructure may be able to influence function. However, the ability to prepare such MCIL-based BCPs by the direct copolymerization of charged MCIL monomers with other co-monomers is challenging because there are often chemical incompatibilities between the polymerization initiators/catalysts and the MCIL monomers. This talk presents an overview of our group’s work in the direct, controlled/living polymerization of charged MCIL monomers with uncharged co-monomers to form uncharged-charged MCIL-based BCPs that exhibit functional properties. Specifically, we synthesized an MCIL-based uncharged-charged BCP platform via controlled radical polymerization that exhibits periodic, phase-separated microstructures and reversibly coordinates protic small molecules with an accompanying color change. This MCIL-based BCP was made by sequential reversible addition-fragmentation chain-transfer polymerization of first butyl methacrylate and then a styrenic phosphonium MCIL monomer with a cobalt(II) bis(salicylate) anion. More recently, we synthesized a magnetically responsive uncharged-charged MCIL-based BCP via the sequential living ring-opening metathesis polymerization of first an uncharged norbornene derivative and then a norbornene imidazolium MCIL monomer containing the strongly paramagnetic iron(III) tetrachloride anion. Preliminary results show that this BCP also forms phase-separated microstructures. The design, synthesis, morphological behavior, and functional properties of these new MCIL-based BCP platforms will be discussed.

Synthesis of metal-containing ionic liquid-based, uncharged-charged diblock copolymers with functional properties

ACS Spring Meeting 2021

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