Effect of Monomer Structure on Curing Behavior, CO2 Solubility, and Gas Permeability of Ionic Liquid-Based Epoxy–Amine Resins and Ion-Gels

New imidazolium- and pyrrolidinium-based bis­(epoxide)-functionalized ionic liquid (IL) monomers were synthesized and reacted with multifunctional amine monomers to produce cross-linked, epoxy–amine poly­(ionic liquid) (PIL) resins and PIL/IL ion-gel membranes. The length and chemical nature (i.e., alkyl versus ether) between the imidazolium group and epoxide groups were studied to determine their effects on CO2 affinity. The CO2 uptake (millimoles per gram) of the epoxy–amine resins (between 0.1 and 1 mmol/g) was found to depend predominately on the epoxide-to-amine ratio and the bis­(epoxide) IL molecular weight. The effect of using a primary versus a secondary amine-containing multifunctional monomer was also assessed for the resin synthesis. Secondary amines can increase CO2 permeability but also increase the time required for bis­(epoxide) conversion. When either the epoxide or amine monomer structure is changed, the CO2 solubility and permeability of the resulting PIL resins and ion-gel membranes can be tuned.