Ion transport in surface functionalized SnO2 nanoparticles dispersed imidazolium ionanofluids: Decoupling from structural relaxation

Abstract

The focus of the present work is the study of conductivity and structural relaxation dynamics of a series of ionanofluids, prepared by dispersing different extents of ionic liquid tethered SnO2 nanoparticles, i.e., nanoscale hybrid ionic fluid, (NHIF) in imidazolium ionic liquid host. Measurements have been made using temperature dependent dielectric spectroscopy and differential scanning calorimetry (DSC). Our study reveals that with increasing NHIF content in the host, the ion conductivity relaxation becomes increasingly faster than the structural relaxation at any measured temperature. For 20.0 wt% NHIF the structural relaxation time is longer than the conductivity relaxation times by more than six decades in the vicinity of the glass transition temperature (Tg), i.e. the decoupling index Rt(Tg) is >6. In contrast to the host ionic liquid, the observed unusual behaviour with increasing NHIF content is appropriately correlated to the corresponding depression of crystallinity and a sharp rise in fragility index in ionanofluids. The study suggests that the conjunction of ionic liquid tethered nanoparticles and ionic liquid provides a promising way to design highly conductive ionanofluids solvents with numerous application perspectives.