Ionic liquid-based semi-interpenetrating polymer network (sIPN) membranes for CO2 separation

• Published in: Separation and purification technology 2021-11, Vol.274, p.118437, Article 118437
• Main Authors: Gouveia, Andreia S.L., Bumenn, Edwin, Rohtlaid, Kätlin, Michaud, Alexandre, Vieira, Tiago M., Alves, Vítor D., Tomé, Liliana C., Plesse, Cédric, Marrucho, Isabel M.
• Format: Article
• Language: English
• Subjects: Chemical Sciences; CO2 separation; Engineering Sciences; Ionic liquids; Material chemistry; Materials; Membranes; Polymers; Semi-interpenetrating polymer network
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2021.118437

[Display omitted] •Ionic liquid (IL)-based semi-interpenetrating polymer network (sIPN) membranes were prepared by swelling method.•Poly(ethylene oxide) (PEO) network and linear nitrile butadiene rubber (NBR) were used to fabricate the sIPN.•Three different ILs were incorporated into the sIPN up to 66 wt%.•The sIPN/IL membranes presented higher IL contents compared to reported poly(ionic liquid) (PIL)–IL membranes with similar ILs.•Higher elongation properties and CO2, H2 and H2 permeabilities were obtained compared to reported PIL–IL composites. This work explores the preparation of ionic liquid (IL)-based semi-interpenetrating polymer network (sIPN) membranes composed of poly(ethylene oxide) (PEO) network and linear nitrile butadiene rubber (NBR), incorporating up to 66 wt% of three ILs with a common cation ([C2mim]+) and different anions ([C(CN)3]–, [NTf2]– and [FSI]–). All sIPN/IL membranes were characterized by Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and puncture tests. Ideal CO2/N2 and CO2/H2 separation performances of the prepared sIPN/IL membranes were investigated at T = 20 °C and 35 °C, respectively, and 1 bar of feed pressure. The incorporation of both [C2mim][NTf2] and [C2mim][FSI] ILs allowed to obtain sIPN/IL membranes with higher IL contents (66 wt%) compared to previously reported PIL–IL membranes with similar IL structures (40 wt%). The membranes containing [NTf2]– and [C(CN)3]– anions showed improved thermal stability compared to the neat PEO/NBR sIPN, being thermally stable up to 300 °C. Although sIPN/IL membrane mechanical properties were affected by the incorporation of IL, all membranes revealed high elongation properties (elongation upon puncture = 68–170%), mainly due to the presence of NBR component in the sIPN structure. The highest CO2/N2 permselectivity was obtained for the sIPN/66 wt% [C2mim][C(CN)3] membrane, while the sIPN/66 wt% [C2mim][FSI] membrane revealed the highest CO2 and N2 permeabilities. The incorporation of 66 wt% of [C2mim][FSI] into the sIPN also showed superior CO2/H2 separation performance, with a CO2 permeability of 727 Barrer and a CO2/H2 permselectivity of 10.9.