In this thesis, we investigated the surface composition and orientation of both pure
room-temperature ionic liquids (Ils) and binary mixtures of the ILs of the type
consisting of the 1-alkyl-3-methylimidazolium ([C[subscropt n]mim]���, n=4, 8, and 12) cation
coupled with either [PF���]���, [BF���]���, [Cl]���, or [Br]���. The surfaces of the ILs were
examined using both direct recoil spectrometry (DRS) and surface tension
measurements. With DRS, a spectral signal produced by a recoiled surface atom
indicates the existence of a particular molecular or ionic species at the interface.
Derived from the signal are the atomic ratios, which are strongly dependent on the
surface orientation of the surface species. The DRS findings are complimented with
surface tension measurements, and the thermodynamics properties (surface enthalpy
and entropy) derived from such measurements are related to the surface composition
and orientation.
From the experiments on the neat ILs, the surface compositions of the imidazolium-based
ILs were determined. Furthermore, the effects of systematic variations of the
cation size (the length of the 1-alkyl chain) and anion identity on the surface
orientation of the organic cation were also examined.
The surfaces of binary mixtures containing ~25 mol % of [C������mim][PF���] or
[C������mim][BF���] in [C���mim}[BF���] were also investigated. The DRS and surface
tension data of the mixtures were compared to those of the pure components to
determine the composition and any changes in the orientations of the cations upon mixing. / Graduation date: 2004
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/31099 |
| Date | 09 December 2003 |
| Creators | Law, George |
| Contributors | Watson, Philip R. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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