title: Nanoscale segregation in room temperature ionic liquids.
abstract: Room-temperature ionic liquids (RTILs) are organic salts that are characterized by low melting points. They are considered to possess a homogeneous microscopic structure. We provide the first experimental evidence of the existence of nanoscale heterogeneities in neat liquid and supercooled RTILs, such as 1-alkyl-3-methyl imidazolium-based salts, using X-ray diffraction. These heterogeneities are of the order of a few nanometers and their size is proportional to the alkyl chain length. These results provide strong support to the findings from recent molecular dynamics simulations, which proposed the occurrence of nanostructures in RTILs, as a consequence of alkyl chains segregation. Moreover, our study addresses the issue of the temperature dependence of the heterogeneities size, showing a behavior that resembles the density one only below the glass transition, thus suggesting a complex behavior above this temperature. These results will provide a novel interpretation approach for the unique chemical physical properties of RTILs.
authors: Istituto per i Processi Chimico-Fisici, Consiglio Nazionale delle Ricerche, via La Farina, 237, I-98123 Messina, Italy.
authors: Alessandro
authors: A
authors: Triolo
authors: Olga
authors: O
authors: Russina
authors: Hans-Jurgen
authors: HJ
authors: Bleif
authors: Emanuela
authors: E
authors: Di Cola
mesh_terms: D052578:Ionic Liquids / Q000737:chemistry*; D010316:Particle Size; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D052578:Ionic Liquids