Probing water-driven nanostructures in an ionic liquid using small- and wide-angle neutron scattering: 1-Dodecyl-3-methylimidazolium iodide

In this study, phase variations within a hydrophilic ionic liquid (IL)–D2O mixture were observed in using small- and wide-angle neutron scattering (SWANS). The specific IL used was 1-dodecyl-3-methylimidazolium iodide ([C12mim][I]). Owing to the large neutron scattering length density of deuterium, D2O nanostructures appeared to be enhanced in the SWANS profile. Moreover, the complicated phase diagram of [C12mim][I]–D2O was determined using SWANS. Evidently, the water-rich region featured nanoconfined water (a water pocket), a smectic A phase, a columnar hexagonal phase as a lyotropic mesophase, a bicontinuous cubic phase as a double gyroid, and a layered crystal phase. Additionally, a double gyroid structure appeared in the narrow water-concentration region.