title: Influence of substituents and functional groups on the surface composition of ionic liquids.
abstract: We have performed a systematic study addressing the surface behavior of a variety of functionalized and non-functionalized ionic liquids (ILs). From angle-resolved X-ray photoelectron spectroscopy, detailed conclusions on the surface enrichment of the functional groups and the molecular orientation of the cations and anions is derived. The systems include imidazolium-based ILs methylated at the C2 position, a phenyl-functionalized IL, an alkoxysilane-functionalized IL, halo-functionalized ILs, thioether-functionalized ILs, and amine-functionalized ILs. The results are compared with the results for corresponding non-functionalized ILs where available. Generally, enrichment of the functional group at the surface is only observed for systems that have very weak interaction between the functional group and the ionic head groups.
authors.affiliation: Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen (Germany), Fax: (+49) 9131-85-28867.
authors.forename: Claudia
authors.initials: C
authors.lastname: Kolbeck
authors.forename: Inga
authors.initials: I
authors.lastname: Niedermaier
authors.forename: Alexey
authors.initials: A
authors.lastname: Deyko
authors.forename: Kevin R J
authors.initials: KR
authors.lastname: Lovelock
authors.forename: Nicola
authors.initials: N
authors.lastname: Taccardi
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.forename: Peter
authors.initials: P
authors.lastname: Wasserscheid
authors.forename: Florian
authors.initials: F
authors.lastname: Maier
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Steinrück
keywords: X-ray photoelectron spectroscopy; functionalized ionic liquids; surface analysis; surface enrichment; surface orientation