Formation of Micelles and Their Sphere-rod Transition of Alkylpyridinium Halides

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Abbreviations: dodecylpyridinium halide X=C: Cl, X=B: Br, X=I: ILight scattering from aqueous solutions of DPC an DPB increases with increasing salt concentration up to 1.0 M NaCl and 0.5 M NaBr, respectively, and then it decreases with increasing salt concentration further. The micelle aggregation number of DPC is as low as 18.6 in water, suggesting formation of porus micelles, and it is 43.5 in 0.05 M NaCl and increases to 71.9 in 4.0 M NaCl, indicating that spherical micelles are formed. On the otherhand, the micelle aggregation number of DPB is 46.0 in water and increases to 70.7 in 0.3 M NaBr, indicating formation of spherical micelles, but it remains to be 70.7 with further increase in NaBr concentration, suggesting that the micelle is compact.Light scattering from aqueous NaI solutions of DPI increases strongly with increasing NaI concentration, especially beyond 0.01 M. The micelle has aggregation number, 71.6, in water and increases to 90.7 in 0.007 NaI, and the micelles are spherical in this range. At higher NaI concentrations rodlike micelles are formed with increasing micelle concentration, and in 0.05 M NaI the aggregation number reaches 1360.For all these micelles the linear doubl linea logarithmic relationships hold between micelle molecular weight and ionic strength.