Simulations of Ionic Liquid on Silica

MD simulations and experimental data lead to different conclusions regarding the role and influence of the anions on cation orientation. There is agreement, however, that both anion size and type and alkyl chain length influence the overall orientation, with the alkyl chain being the primary factor. 

Research work involving the mica-ionic liquid interface via surface analytical techniques, such as atomic force microscopy (AFM), was carried out by Horn et al. [38] and Atkin and Warr [39] with information on the structuring of the ionic liquid at the EDL (see also Chapter 1). Their studies identified the formation of bilayer structures and strong mica-ionic liquid interaction, presumably due to the high mica surface charge [35, 36]. 

Silica surfaces with lower surface charge are distinctly different from mica surfaces and are usually of greater importance in catalytic processes where they constitute the primary support material in supported ionic Hquid phase (SILP) catalysis. The structural arrangement of ionic liquid studied by surface analytical techniques, UHV techniques, in particular, point toward preferential cation enrichment at the innermost surface layers. 

Ionic liquids at the gas-liquid and solid-liquid interface have been extensively studied by a variety of surface analytical techniques. The most prominent technique for surface orientational analysis proves to be SFG. Other vibrational spectroscopic and surface-sensitive techniques such as surface-enhanced Raman spectroscopy (SERS) and total internal reflection Raman spectroscopy (TIR Raman) have been employed for studying surface processes these techniques, however, have not been applied yet specifically for the study of ionic hquids. 

The overall information gathered gives a detailed description of ionic liquids on various interfaces. The large numbers of ionic hquids that have been studied 

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