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

Ana R Nabais,Luísa A Neves,Rute O Francisco,Liliana C Tomé,Vítor D Alves

doi:10.3390/membranes11120998

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.

Highlights

In the last 25 years, numerous studies have been focusing on ionic liquids (ILs), a material with exceptional features that keeps stimulating researchers’ curiosity today.Besides being liquid salts at room temperature due to their melting points below 100 ◦ C, ILs are characterized by distinct tunable properties [1,2]
This work focuses on the use of ILs for carbon dioxide (CO2 ) separation from light gases taking advantage of the interactions established between the electrical charges of the IL and the quadrupole of CO2 molecules, and combining them with membrane technology, an economic and environmentally friendly approach to CO2 capture [8,9,10]
Attenuated Total Reflectance Fourier-Transform Infrared (ATR-FTIR) spectroscopy was performed to confirm the incorporation of the IL, poly(ethylene glycol) diacrylate (PEGDA), and MMT into the iongel membranes, verify possible interactions established between them, and confirm the occurrence of the photopolymerization reaction

Summary

Introduction

In the last 25 years, numerous studies have been focusing on ionic liquids (ILs), a material with exceptional features that keeps stimulating researchers’ curiosity today.Besides being liquid salts at room temperature due to their melting points below 100 ◦ C, ILs are characterized by distinct tunable properties [1,2]. In the last 25 years, numerous studies have been focusing on ionic liquids (ILs), a material with exceptional features that keeps stimulating researchers’ curiosity today. The most appealing property of ILs is their designable nature, which allows the preparation of task-specific materials for the envisioned application by the combination of different ions and the addition of specific functional groups [1]. This work focuses on the use of ILs for carbon dioxide (CO2 ) separation from light gases taking advantage of the interactions established between the electrical charges of the IL and the quadrupole of CO2 molecules, and combining them with membrane technology, an economic and environmentally friendly approach to CO2 capture [8,9,10]

Objectives

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Conclusion