Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 14: Organic, polymeric, biomolecular films – also with absorbates I
O 14.5: Vortrag
Montag, 23. März 2009, 16:00–16:15, SCH A316
The Effect of Different Substituents on the Surface Composition of Ionic Liquids - An ARXPS study (interchanged with O 14.6) — •Claudia Kolbeck1, Kevin Robert John Lovelock1, Till Cremer1, Natalia Paape2, Peter Wasserscheid2,3, and Hans-Peter Steinrück1,3 — 1Lehrstuhl für Physikalische Chemie II, Egerlandstr. 3, 91058 Erlangen — 2Lehrstuhl für Chemische Reaktionstechnik, Egerlandstr. 3, 91058 Erlangen — 3Erlangen Catalysis Resource Center (ECRC)
A molecular understanding of ionic liquid (IL) surfaces is essential in order to explain related macroscopic properties such as surface tension. Due to their low vapour pressure ILs, i.e., molten salts with melting points below 100 ∘C, can be studied employing surface science techniques under ultra-high vacuum conditions. Angle resolved X-ray photoelectron spectroscopy (ARXPS) was used to investigate the change in surface composition of imidazolium based ionic liquids (ILs) by systematic variation of non-functionalised and functionalised groups attached to the molecules. For [CnMIm][Tf2N] (n = 2-16) with saturated carbon chains of different length as substituents of the imidazolium cation, a surface enrichment of the chains was clearly observed for n ≥ 4. Enrichment of the aliphatic carbon also occurs for alkyl groups attached to the anion as observed for [C2MIm][C8OSO3].[1] Poly(ethyleneglycol)ether functionalities introduced in the cation chain, however, lead to a stoichiometric surface composition, and, thus, to no enrichment of the chains.[2]
[1] K. R. J. Lovelock et al., submitted to J. Phys. Chem. B.
[2] C. Kolbeck et al., Langmuir 2008, 24, 9500.