High pressure studies of the transport properties of ionic liquids

High pressure measurements have been made of viscosities, ion self-diffusion coefficients and electrical conductivities of ionic liquids, mainly of imidazolium salts. We review how these properties have been analysed in terms of the empirical Stokes-Einstein, Walden and Nernst-Einstein equations, and examine trends revealed by the phenomenological approach of velocity correlation coefficients and the more general theory of density scaling. Finally we examine the possibility of dynamic crossover in the transport properties of ionic liquids.