In binary systems or mixtures, the ratio of the components has a notable effect on the surface activity. In this study, the critical micelle concentration (CMC) and surface tension of aqueous solutions at the CMC for ILs A and B and DSILs at various molar ratios (AB0.1-AB0.9) were determined. All the studied systems were characterized by high surface activity and can be considered as surface-active ILs (SAILs). The obtained data are depicted in Fig. , and the exact values are provided in Table .12 (Supplementary Data). reported for mixtures of anionic/cationic and ionic/nonionic surfactants. These nonadditive effects in surfactant mixtures stem predominantly from the entropy of the diffuse counterion layer outside the micelle interfacial boundaries, as well as the lengths of the tails and the charges in the cation and anion .