De Novo Design of Liquid-Free, Solid-State Ionogel Membranes Based on Polymerizable Deep Eutectic Solvent for Highly-Selective CO2 Separation

Ionic liquids (ILs)-based separation membranes have been recognized as appealing platforms to achieve preferential CO 2 capture. Despite remarkable achievements, these ILs-based membranes are largely restricted by the inferior perm-selectivity of CO 2 and the use of high-cost, difficult-to-scale ILs. Here, a new kind of liquid-free, solid-state ionogel membranes (IGMs) is presented by virtue of green, low-cost, and mass-producible polymerizable deep eutectic solvent consisting of acrylic acid and choline chloride. Leveraging Janus membranes as confined reactor, polymerizable deep eutectic solvent can be well confined within the wettability-compatible layer of Janus membranes and be rapidly polymerized into thickness-tunable liquid-free, solid-state ionogel as CO 2 -philic selective network. It is shown that the selective layer thickness of IGMs can be decreased by 10 folds over counterpart meanwhile possessing an enhanced breakthrough pressure, enabling a high and stable CO 2 permeance even under repeated mechanical friction and bending. Moreover, these IGMs take advantage of their liquid-free, solid-state dense CO 2 -philic network to give an extraordinary CO 2 /N 2 selectivity as high as 150, transcending most of ILs-based membranes (< 60). The material building block and toolkit developed in this work can unleash the potential of polymerizable deep eutectic solvent and beyond in the field of gas separation membranes.