Development of a Micro-Double-Network Ion Gel-Based CO2 Separation Membrane from Nonvolatile Network Precursors

A micro-double-network (μ-DN) ion gel membrane was fabricated using nonvolatile network precursors comprising a presynthesized cross-linkable polymer as the organic part, silica nanoparticles as the inorganic part, and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim][Tf2N]). The mechanical properties of the ion gel were effectively improved through optimizing the molecular weight of the cross-linkable polymer and the organic/inorganic network composition. The μ-DN ion gel membranes exhibited the CO2 permeability of approximately 920 Barrer under atmospheric pressure, which is much higher than those of the classic double-network ion gel membranes fabricated using volatile network precursors (556 Barrer) and the supported ionic liquid membranes (617 Barrer). The membrane also has good pressure resistance and long-term stability. The μ-DN ion gel membrane formed by nonvolatile network precursors shows good mechanical properties and high CO2 separation performance, which make it a good candidate base material for developing high-permeance thin ion gel membranes.