ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 37, Number 1
JKCSEZ 37(1)
February 20, 1993 

The effects of added alcohols on the critical micelle concentration(CMC) of cetylpyridinium bromide(CPB) were investigated by the UV-Vis spectrophotometer at the temperature range of 8∼45℃. The CMC of CPB was increased with the addition of methanol in the whole temperature region studied, while decreased with the addition of ethanol and propanol. The increase of CMC with the addition of methanol may be attributable to the increasing solvent power of the methanol-water mixture, because methanol was scarcely solubilized into the palisade layer of the micelle of CPB. The decrease of CMC with the inclusion of ethanol and propanol may be derived from the solubilization of alcohols into the micelles. On the other hand, the CMC was decreased with the temperature rise in the low-temperature region below about 25C, and the CMC was increased in the high-temperature region above that. The thermodynamic parameters (△GMo, △HMo, and △SMo) of the micellization of CPB were obtained in some aqueous alcohol solutions. In the whole temperature region (8∼45℃), the values of △GMo were negative, while those of △SMo were positive. And in the temperature region below about 25℃ the △HMo values were positive, while in the temperature region above that the values were negative.