(537c) Structure and CO2 Capture Properties of Polyanionic Films Containing Perfluoroalkyl Sulfonylimide

Poly(ionic liquids) (PolyILs) with excellent mechanical stability and strong CO₂ affinity have emerged as an exciting platform for membrane carbon capture. This study aims to systematically evaluate the effect of fluorine content on structure characteristics and CO₂/gas separation properties of novel anionic PolyIL membranes. First, ionic liquid of 1-ethyl-3-methylimidazolium 3-acryloxypropylsulfonyl(-perfluoroalkyl-[sulfonimide]) with 3, 5 or 9 fluorine groups (or EF3, EF5 and EF9, respectively) were prepared via Sulfur(VI) Fluoride Exchange (SuFEx) click chemistry. These ILs can be cross-linked with 2 mol% of poly(ethylene glycol) diacrylate (PEGDA) to obtain mechanically stable PolyILs (ie. PolyEF) membrane for CO₂ separation application. Characterization of these PolyEF membranes is systematically investigated via FTIR, DSC, TGA, XRD, gas sorption and permeation apparatus. For example, increasing the flourine content between PolyEF3 and PolyEF9 increases the glass transition temperature from -39 to -12^oC, and increases the counterion d-spacing from 0.43 to 0.48 nm, respectively, and enhances CO₂ permeability from 17 to 35 Barrer, and CO₂/N₂ from 10 to 17, respectively. Interestingly, free EF ionic liquid loaded PolyEFs exhibit reduction in T_g but enhancement in counterion d-spacing and simultaneous improvement in gas permeability and CO₂/gas selectivity for all samples. For instance, addition of 57wt% of EF3 in PolyEF3 decreases the T_g from -39 to -67^oC, respectively, but enhances CO₂ permeability from 17 to 260 Barrer, and CO₂/N₂ from 10 to 28, respectively. Direct correlation between polymer transition temperature and gas transport properties can be satisfactorily described by the Vogel-Fulcher-Tammann (VFT) equation. This systematic study highlights the attractive CO₂/gas separation properties of polyanionic liquid membranes, providing insight into the design of polyILs membranes for practical CO₂ capture applications.