Poly(ethylene glycol) Diacrylate Iongel Membranes Reinforced with Nanoclays for CO2 Separation

Abstract

Despite the fact that iongels are very attractive materials for gas separation membranes, they often show mechanical stability issues mainly due to the high ionic liquid (IL) content (≥60 wt%) needed to achieve high gas separation performances. This work investigates a strategy to improve the mechanical properties of iongel membranes, which consists in the incorporation of montmorillonite (MMT) nanoclay, from 0.2 to 7.5 wt%, into a cross-linked poly(ethylene glycol) diacrylate (PEGDA) network containing 60 wt% of the IL 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][TFSI]). The iongels were prepared by a simple one-pot method using ultraviolet (UV) initiated polymerization of poly(ethylene glycol) diacrylate (PEGDA) and characterized by several techniques to assess their physico-chemical properties. The thermal stability of the iongels was influenced by the addition of higher MMT contents (>5 wt%). It was possible to improve both puncture strength and elongation at break with MMT contents up to 1 wt%. Furthermore, the highest ideal gas selectivities were achieved for iongels containing 0.5 wt% MMT, while the highest CO2 permeability was observed at 7.5 wt% MMT content, due to an increase in diffusivity. Remarkably, this strategy allowed for the preparation and gas permeation of self-standing iongel containing 80 wt% IL, which had not been possible up until now.

Facilitated transport membrane with functionalized ionic liquid carriers for CO2/N2, CO2/O2, and CO2/air separations

“…23 Conventional solution-diffusion (S-D) gas separation membranes rely on the difference in solubility and diffusivity of the target gas over other gas components for separation. 24 Recent progresses on the S-D membranes focused on increasing (1) the solubility selectivity toward CO 2 over other gases by the incorporation of highly polar or ionic components; [25][26][27][28][29] and (2) the diffusivity selectivity for CO 2 sieving by rigid polymeric backbones with high free volume. [30][31][32][33][34] There is usually a tradeoff between gas permeance and selectivity of a membrane, as described by the Robeson upper-bound.…”