Stability of supported ionic liquid membranes as studied by X-ray photoelectron spectroscopy

Additionally, X-ray photoelectron spectroscopy (XPS) was used to characterise the SLMs obtained by immobilizing the ionic liquids [CnMIM][PF6] (n = 4, 8) and [C10MIM][BF4] in a polyvinylidene fluoride (PVDF) supporting membrane. This technique allows for the determination of the surface chemical composition of a sample and was used for the characterization of both the supported liquid membranes and the ionic liquids. The SLMs were analysed immediately after preparation and after being immersed for 1 week in de-ionised water. This way, it was possible not only to assess the presence of the RTILs in the membrane after preparation, but also to identify whether there were any chemical modifications on the SLMs' surface after contact with an aqueous solution, thus obtaining valuable information about their integrity and stability.