FLUORESCENCE PROBE STUDIES ON THE SECOND CRITICAL MICELLE CONCENTRATION OF SEVERAL KINDS OF SURFACTANTS |
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| Authors: | Li Fang Li GanZuo Zhai LiMin Zheng LiQiang Wang HongLi |
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| Institution: | 1. Chemistry Department , Shandong University , Jinan, 250100, China;2. Chinese Academyof Sciences , Institute of Chemical Physics , Lanzhou, 730000, China |
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| Abstract: | The fluorescence intenstiy ratios (F2/F1) of excimer (F2) to monomer (F1) of probe (pyrene) were measured as a function of the concentration of the surfactant in several systems, which consist of sodium hexadecyl sulfonate (C16As)-anionic surfactant, cetyltrimethylammonium bromide (CTAB)-cationic surfactant and pentaoxyethylene decyl ether (C10E5)-nonionic surfactant. The second CMC values were obtained according to F2/F1 ~ surfactant concentration curve break. In addition, we also studied the variation of second CMC vs NaCl concentration. It was found that the second CMC values of C16A5 and CTAB decreased with the increase of NaCl concentration. But the present of NaCl had no influence on the second CMC value of C10E5. Results showed that sphere-shaped micelles turn into rod-like micelle at the second CMC. The results were interpreted in terms of diffusion of pyrene molecules and the distribution of pyrene among micelles. |
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