Du, Changfei, Cai, Dongxing, Qin, Miao, Zheng, Peizhu, Hao, Zhiguo, Yin, Tianxiang, Zhao, Jihua, and Shen, Weiguo
Mixedsurfactant solutions are studied to understand their synergisticeffects. Here we report the micellization properties of mixed surfactantsolutions of the gemini surfactant N,N′-bis(dimethyldodecyl)-1,2-ethanediammoniumdibromide (12–2–12)with the imidazolium ionic liquid 1-dodecyl-3-methylimidazolium bromide(C12mimBr) investigated by isothermal titration calorimetry(ITC), conductometry, fluorimetry, and dynamic light scattering (DLS).A two-parameter Margules model was successfully used to correlatethe cmc values and calculate the compositions and activity coefficientsof the two components in the mixed micelle phase for 12–2–12/C12mimBr aqueous solutions with different overall surfactantcompositions. The dissociation degree of counterion, the thermodynamicquantities of micellization, and the excess thermodynamic quantitiesfor the mixed micelle were calculated and discussed. The ITC experimentin the low overall surfactant composition region showed a second phasetransition. A thermodynamic model was proposed to explore phase behaviorsof two different types of micelle and their solution, which was furtherconfirmed by fluorescence and DLS studies. [ABSTRACT FROM AUTHOR]