Highly selective CO2 permeable double-network ionogel membrane containing 1-ethyl-3-methylimidazolium dicyanamide

A double-network (DN) ionogel membrane containing 1-ethyl-3-methylimidazolium dicyanamide ([C2mim] [DCA]) was developed and evaluated for its mechanical robustness and its CO2 permeation properties. Polyvinyl alcohol (PVA) was used as the initial network for the DN ionogel membrane. It forms a partially-crystalline physical crosslinking within [C2mim][DCA] and acts as a sacrificial bond to toughen the ionogel. A loosely crosslinked poly(N,N-dimethylacrylamide) (PDMAAm) network was formed by free-radical polymerization to interpenetrate with the physically crosslinked PVA network. The more the gel was elongated, the more the physical crosslinking in the PVA network were broken and the more energy was dissipated. As a result, the ion gel toughened. Owing to its excellent toughness, the developed DN ionogel membrane retained 93 wt% of [C2mim][DCA] and exhibited the CO2 permeability and the CO2 perm-selectivity over N2 of 2920 barrer and 61, respectively, the highest level of CO2 separation performance among the latest CO2 separation membranes. The DN ionogel membrane kept the CO2 separation performance required for CO2 capture from flue gases from coalfired power plants even at 80 degrees C and 80 % relative humidity.