title: Influence of different substituents on the surface composition of ionic liquids studied using ARXPS.
abstract: Angle resolved X-ray photoelectron spectroscopy has been used to study the surface composition of various nonfunctionalized and functionalized 1,3-dialkylimidazolium ionic liquids. For [CnC1Im][Tf2N] (where n = 2-16), an enrichment of the aliphatic carbon was observed for longer chains (n > or = 4). Enrichment of the aliphatic carbon also occurs for alkyl chains attached to the anion, as observed for [C2C1Im][OcOSO3]. Oligo(ethyleneglycol)ether (PEG) functionalities in the cation lead to a surface composition close to bulk stoichiometry and thus a loss in enrichment of the chains. This effect is attributed to attractive interactions between the oxygen atoms on the cation to the hydrogen atoms on the imidazolium ring for [Et(EG)2MIm] [Tf2N] and [Me(EG)3MIm][Tf2N].
authors.affiliation: Lehrstuhl für Physikalische Chemie II, Lehrstuhl für Chemische Reaktionstechnik, Erlangen Catalysis Resource Center (ECRC), Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany.
authors.forename: K R J
authors.initials: KR
authors.lastname: Lovelock
authors.forename: C
authors.initials: C
authors.lastname: Kolbeck
authors.forename: T
authors.initials: T
authors.lastname: Cremer
authors.forename: N
authors.initials: N
authors.lastname: Paape
authors.forename: P S
authors.initials: PS
authors.lastname: Schulz
authors.forename: P
authors.initials: P
authors.lastname: Wasserscheid
authors.forename: F
authors.initials: F
authors.lastname: Maier
authors.forename: H-P
authors.initials: HP
authors.lastname: Steinrück