Pore-Networked Gels: Permanently Porous Ionic Liquid Gels with Linked Metal-Organic Polyhedra Networks

Porous liquids (PLs) are attractive materials becauseof theircapability to combine the intrinsic porosity of microporous solidsand the processability of liquids. Most of the studies focus on thesynthesis of PLs with not only high porosity but also low viscosityby considering their transportation in industrial plants. However,a gap exists between PLs and solid adsorbents for some practical cases,where the liquid characteristics and mechanical stability withoutleakage are simultaneously required. Here, we fill in this gap bydemonstrating a new concept of pore-networked gels, in which the solventphase is trapped by molecular networks with accessible porosity. Toachieve this, we fabricate a linked metal-organic polyhedra(MOPs) gel, followed by exchanging the solvent phase with a bulkyliquid such as ionic liquids (ILs); the dimethylformamide solventtrapped inside the as-synthesized gel is replaced by the target IL,1-butyl-3-methylimidazolium tetrafluoroborate, which in turn cannotenter MOP pores due to their larger molecular size. The remainingvolatile solvents in the MOP cavities can then be removed by thermalactivation, endowing the obtained IL gel (Gel_IL) withaccessible microporosity. The CO2 capacities of the gelsare greatly enhanced compared to the neat IL. The exchange with theIL also exerts a positive influence on the final gel performancessuch as mechanical properties and low volatility. Besides ILs, variousfunctional liquids are shown to be amenable to this strategy to fabricatepore-networked gels with accessible porosity, demonstrating theirpotential use in the field of gas adsorption or separation.