Investigating the Properties and Phase Behavior of Ionic Liquid and Polymer Blends

Atmospheric carbon dioxide (CO₂) traps heat and increases global temperatures. Both ionic liquids (ILs) and polymers have been investigated for use in CO₂ capture technologies. However, composite polymer/IL materials could enhance capture and maintain favorable physical properties for industrial usage. Previously, we identified 1-hexyl-3-methylimidazolium bis(trifuloromethylsulfonyl)imide ([hmim][Tf₂N]) as an IL with excellent physical CO₂ solubility. We are interested in polyether and ionic liquid composite materials specifically because of the favorable interactions polyethers have with CO₂. It is a necessary first step to investigate the phase behavior and properties of these blends.

We present results of the phase behavior of [hmim][Tf₂N] blends with hydrophobic polyethers that have appreciable CO₂ solubility. The polymers studied include poly(n-butyl glycidyl ether), poly(allyl glycidyl ether), and poly(isopropyl glycidyl ether). Phase behavior was probed using DSC, microscopy and turbidimetry. The effect of the pendant functional groups in the glycidyl ether polymers (isopropyl vs. n-butyl, and the presence of the double bond in the allyl version) was investigated using 2D NMR and FTIR spectroscopies.