Identification of Sub‐Regions for Ionic Microemulsions Formed With Hydrophilic Ionic Liquid: A Broadband Dielectric Spectroscopy Study

ABSTRACT The sub‐region phase behaviors and percolation dynamics of the ionic microemulsion cetyltrimethylammonium bromide (CTAB)/1‐ethyl‐3‐methylimidazolium‐ethylsulfate (emim‐EtSO 4 )/oil (toluene + pentanol) were studied by dielectric spectroscopy. Two relaxations were observed at ~1 ns and ~60 ps, respectively. These two relaxations were identified as dipole polarization, although they are induced by different molecular groups. The concentration dependence of relaxation parameters on ionic liquids (IL), obtained by fitting Cole‐Cole equations to the dielectric data, was used to probe the microstructure and percolation behavior of the microemulsion. The critical concentrations C p and C 2 , which effectively determine the percolation dynamics, were obtained by analyzing the dependence of the conductivity and permittivity on IL concentration. The static percolation behavior of this system was verified by the scaling relationship between the conductivity and IL concentration. The microstructure of the oil‐IL interface in the bicontinuous phase has been inferred, which helps to reveal the essence of the percolation dynamics.