Amphiphile Meets Amphiphile: Beyond the Polar-Apolar Dualism in Ionic Liquid/Alcohol Mixtures.
The mesoscopic morphology of binary mixtures of ethylammonium nitrate (EAN), the protic ionic liquid par excellence, and methanol is explored using neutron/X-ray diffraction and computational techniques. Both compounds are amphiphilic and characterized by an extended hydrogen bonding network: surprisingly, though macroscopically homogeneous, these mixtures turn out to be mesoscopically highly heterogeneous. Our study reveals that even in methanol-rich mixtures, a wide distribution of clusters exists where EAN preserves its bulk, sponge-like morphology. Accordingly methanol does not succeed in fully dissociating the ionic liquid that keeps on organizing in a bulk-like fashion. This behavior represents the premises to the more dramatic phenomenology observed with longer alcohols that eventually phase separate from EAN. These results challenge the commonly accepted polar and apolar moieties segregation in ionic liquids/molecular liquids mixtures and the current understanding of technologically relevant solvation processes.
†Department of Chemistry, Sapienza University of Rome, 00185 Rome, Italy.
Olga
O
Russina
†Department of Chemistry, Sapienza University of Rome, 00185 Rome, Italy.
Alessio
A
Sferrazza
†Department of Chemistry, Sapienza University of Rome, 00185 Rome, Italy.
Ruggero
R
Caminiti
‡Laboratorio Liquidi Ionici, Istituto Struttura della Materia, Consiglio Nazionale delle Ricerche, 00133 Rome, Italy.
Alessandro
A
Triolo
Critical Phenomena; Heterogeneous Morphology; Mesoscopic Correlation; Protic Ionic Liquids; Small and Wide Angle X-ray Scattering