Aggregation behavior of COOH-functionalized imidazolium-based surface active ionic liquids in aqueous solution

► A novel series of COOH-functionalized imidazolium-based surface active ionic liquids was synthesized. ► The acid SAILs have more superior surface activity than the conventional imidazolium-based SAILs, homologues. ► The relationship between cmc and temperature for [N-C12, N'-CO2H-Im]Br indicates a minimum cmc exists at about 38 °C.