Ion Gel Membrane with Tunable Inorganic/Organic Composite Network for CO₂ Separation

Abstract

A highly tough ionic liquid (IL)-based gel membrane with a specific inorganic/organic composite network is fabricated. Owing to the inorganic/organic composite network, the composite ion gel membrane with 80 wt % of IL shows excellent pressure resistance. The mechanical and gas permeation properties of the composite ion gel membrane can be controlled by changing the inorganic/organic network composition as well as the cross-linking degree of the organic polymer network. Although the mechanical and gas permeation properties show a trade-off relationship with the normal ion gel, the composite ion gel membrane, which has a relatively low composition of loosely cross-linked organic polymer network, exhibited not only high CO2 permeability but also high mechanical strength. The composite ion gel membrane with an optimized network composition achieved CO2 permeability of approximately 1850 barrer and a CO2/N2 selectivity of 20 for more than 300 h at 50 °C under humid conditions.

Soft materials based on colloidal self-assembly in ionic liquids

“…there have been several reports on IL-based separation membranes in this area of research. [5][6][7] Introduction of solid-like mechanical properties into ILs is generally achieved by forming organic or inorganic three-dimensional networks in ILs. Polymer gels containing ILs can be prepared by in-situ polymerization of monomers and cross-linkers 8 or by self-assembly of ABA tri-block copolymers 9 , where the A and B segments are insoluble and soluble in the ILs, respectively.…”

Toluene vapor removal using an inorganic/organic double-network ion gel membrane

“…The inorganic/organic DN ion gel membrane was prepared based on the procedure written in elsewhere. [45,47] The DN ion gel membrane was prepared by one-pot/two-step process. A certain amount of TEOS and formic acid for inorganic network formation was added in [C 4 mim][Tf 2 N] and agitated for more than 2 hours to dissolve them completely.…”

“…The order of the reported benzene vapor permeabilities was same as the toluene vapor permeability of the SILM we prepared. In addition, regarding N 2 permeability, we previously reported the N 2 permeability of an SILM containing [C 4 mim][Tf 2 N] for CO 2 /N 2 binary system at 303 K under atmospheric pressure condition [46,47] and the obtained N 2 permeability was 35 barrer. This is almost same to that obtained for the SILM prepared in this work.…”

“…The developed DN ion gel membranes consisted of the specific network and a large amount of an IL exhibited gas permeability and separation performance higher than SILMs with the same IL. [46,47] To synthesize the DN ion gel membrane, the inorganic component was formed by thermally induced polycondensation of tetraethylorthosilicate (TEOS), and the polymer network was formed by UV-initiated free-radical polymerization of N,N-dimethylacrylamide (DMAAm). TEOS polycondensation resulted in the formation of silica nanoparticles which were inter-connected by weak physical interactions like hydrogen bonding and van der Waals forces to form a three-dimensional (3D) silica particle network in the IL.…”

Tough and stretchable inorganic/organic double network ion gel containing gemini-type ionic liquid as a multiple hydrogen bond cross-linker

“…In fact, our previous study indicated that a decrease in the fracture strain of the inorganic/organic DN ion gels lead to a decrease in the toughness. 10 In addition, because the dissipated energy of the m-DN ion gels was monotonically increased by increasing the strain up to the fracture point, 7 it was concluded that many unbroken silica particle network clusters still remained in the fractured m-DN ion gel. Therefore, it is expected that if the fracture strain of the m-DN ion gels was increased, more silica particle network clusters would be fractured, which leads to an increase in the toughness of the m-DN ion gels.…”