UV-Polymerized Vinylimidazolium Ionic Liquids for Permselective Membranes.

Fridolin O Sommer,Sylvia Speller,Udo Kragl,Jana-Sophie Appelt,Ingo Barke

doi:10.3390/membranes10110308

Abstract

Ionic liquids are highly charged compounds with increasing applications in material science. A universal approach to synthesize free-standing, vinylalkylimidazolium bromide-containing membranes with an adjustable thickness is presented. By the variation of alkyl side chains, membrane characteristics such as flux and mechanical properties can be adjusted. The simultaneous use of different ionic liquids (ILs) in the synthesis can also improve the membrane properties. In separation application, these charged materials allowed us to retain charged sugars, such as calcium gluconate, by up to 95%, while similar neutral compounds such as glucose passed the membrane. An analysis of the surface conditions using atomic force microscopy (AFM) confirmed the experimental data and explains the decreasing permeance and increased retention of the charged sugars.

Highlights

Pure salts with a melting point below 100 ◦ C, so-called “ionic liquids” (ILs), have remarkable properties such as low vapor pressure and non-flammability [1,2,3]
We report the synthesis of vinylimidazolium-based polymerized ionic liquids as free-standing nanofiltration membranes
The synthesized membranes are flat sheets obtained by UV-induced polymerization of a casting solution containing the ionic liquid (IL), other monomers, a crosslinker (CL) and a photo initiator (PI)

Summary

Introduction

Pure salts with a melting point below 100 ◦ C, so-called “ionic liquids” (ILs), have remarkable properties such as low vapor pressure and non-flammability [1,2,3] Due to their synthetic origin, a large number of combinations of anions and cations is possible, as well as the implementation of functional groups [4]. Used structures of cations and anions of ILs are imidazolium, pyrrolidinium, phosphonium and halogenide ions [5] Polymerizable groups, such as vinyl functions, enable one to fix the charges of ionic liquids in materials [6]. Different states of the material, thermal properties or conductivity are dependent on the choice of monomers or crosslinkers [21] and on the synthetic strategy [15,22,23].

Methods

Results

Conclusion