(63g) Structure and Dynamics of Mixtures of Ionic Liquids and Polyethers

Ionic liquids are salts that remain
liquid near ambient temperatures. Characteristics such as extremely low vapor
pressure and excellent thermal stability have led them to receive significant
attention as potential solvents for separation processes and a plethora of
other applications. One drawback of ionic liquids, however, is that they tend
to be more viscous than conventional solvents. The large viscosity may be a
limiting factor for the use of ionic liquids in industrial operations due to high
mass transfer resistance and increased pumping and handling costs. One strategy
being used to reduce the viscosity of ionic liquids is to mix them with small
amounts of low viscosity additives such as polyethers
or other low volatility fluids. 

In order to understand the
role additives have on the structure and dynamics of ionic liquids, we have
carried out extensive molecular dynamics simulations on mixtures containing imidazolium-based ionic liquids and polyethers.
Viscosities, self-diffusivities and rotational dynamics were computed as a
function of polyether concentration and temperature. Structural properties such
as radial and spatial distribution functions and end-to-end vectors were
computed and used to help understand the trends in the dynamics. Comparison
with available experimental data shows that the simulations are able to
accurately capture both pure fluid and mixture dynamics.