A systematic molecular simulation study of ionic liquid surfaces using intrinsic analysis methods

• Type: Article in International Scientific Journal
• Date: 2012

Authors

Gyoergy Hantal (Author) Other; Iuliia Voroshylova (Author) Other; Natalia N D S Cordeiro (Author) FCUP; Miguel Jorge (Author) Other

Journal

Title: Physical Chemistry Chemical Physics

Vol. 14

Pages: 5200-5213

ISSN: 1463-9076

Publisher: Royal Society of Chemistry

Indexing

ISI Web of Knowledge - 61 Citations

Scopus - 63 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-002-GS9

DOI: 10.1039/c2cp23967a

Abstract (EN): In this paper, we apply novel intrinsic analysis methods, coupled with bivariate orientation analysis, to obtain a detailed picture of the molecular-level structure of ionic liquid surfaces. We observe pronounced layering at the interface, alternating non-polar with ionic regions. The outermost regions of the surface are populated by alkyl chains, which are followed by a dense and tightly packed layer formed of oppositely charged ionic moieties. We then systematically change the cation chain length, the anion size, the temperature and the molecular model, to examine the effect of each of these parameters on the interfacial structure. Increasing the cation chain length promotes orientations in which the chain is pointing into the vapor, thus increasing the coverage of the surface with alkyl groups. Larger anions promote a disruption of the dense ionic layer, increasing the orientational freedom of cations and increasing the amount of free space. The temperature had a relatively small effect on the surface structure, while the effect of the choice of molecular model was clearly significant, particularly on the orientational preferences at the interface. Our study demonstrates the usefulness of molecular simulation methods in the design of ionic liquids to suit particular applications.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 14