The occurrence of the above-described synergistic effect in DSILs makes combining two active surfactants at a well-defined ratio to reduce the amount of surfactants introduced into the environment a legitimate strategy. Synthetic auxins are more efficient when applied in aqueous solutions with the addition of a surface-active adjuvant; therefore, DSILs with surface-active cations and pesticidal anions can guarantee excellent efficacy without the need for the use of other additives . The high surface activity of the analyzed ILs and DSILs means that there is no measurable difference in density and refractive index between their aqueous solutions at CMC and pure water (Supplementary Data, Table . Furthermore, the analysis of the surface tension of the aqueous solution for DSILs AB0.1-AB0.9 and ILs A and B at their respective CMCs indicated a linear dependence on xdic, as illustrated in Fig. . The lack of significant deviation from the linear relationship (R > 0.98) indicates a lack of unexpected interactions in the analyzed systems with water and air .