ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 36, Number 1
JKCSEZ 36(1)
February 20, 1992 

The critical micelle concentration(CMC) values of Dodecylpyridinium bromide(DoPB) were determined by an electric conductivity method at 1∼2000 bars and 25℃. The CMC of DoPB increases with the addition of urea in the whole pressure region studied, and the CMC increases with an increase of the pressure in the low-pressure region, while in the high-pressure region the CMC decreases. The partial molar volume change (△V_m^o) on micellization was also investigated in some urea aqueous solutions. The change (△V_m^o) was reduced by the addition of urea. The results suggest that the "iceberg" structure of water around the hydrocarbon chain of the monomeric surfactant is effectively broken down by urea.