Polymerization of a Imidazolium Ionic Liquid Under 2D Confinement and the Resulting Effects on Ion Dynamics

We have employed broadband dielectric spectroscopy to probe ion dynamics in 1-ethyl-3-vinylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid (IL) under confinement within ~7nm nanoporous silica membranes. The IL was then polymerized within the pores to a maximum monomer conversion of ~70% as determined using Raman spectroscopy. Compared to the pure systems in bulk, the confined PIL displayed increased ionic conductivity, while the IL displayed decreased ionic conductivity under confinement. To unravel the effects of unconverted monomer and the effects of confinement on the increased ion conduction in the PIL system, a blend of the IL and PIL was prepared at the same monomer to polymer ratio as was achieved during polymerization within the membranes. Decreased conductivity in bulk compared to confinement is described due to aggregation of the IL in the blend with that does not occur within the membranes due to free volume effects. These results are also compared to recent theoretical results from the literature.