Developing Distinct Chemical Environments in Ionic Liquid Films

Abstract

We report the reversible transitions from two distinct chemical environments (interfacial and bulk) to a single, globally ordered dominant environment that extends to 800 nm, within two triflate-based ionic liquid (IL) films. Vibrational spectra for supported IL films exhibit multiple peaks for the same vibrational mode, indicating the presence of multiple chemical environments (interfacial and bulk) in the film. After a quiescent maturation time, the vibrational spectra show much simpler absorption profiles indicating coalescence of the IL molecules into a global preferred phase, which resembles the interfacial environment that propagates throughout the film as a function of time. Data analysis suggests significant reorientation of the triflate anion with small changes of the cation, indicating a weakly interacting cation–anion pair. The distal extent of the self-organization is much thicker than that generally reported for solid–fluid interfaces. The ordering is reversible on replenishing the film with ...