A temperature study on critical micellization concentration (CMC), solubility, and degree of counterion binding of alpha-sulfonatomyristic acid methyl ester in water by electroconductivity measurements

For a sodium salt of alpha-sulfonatomyristic acid methyl ester (14SFNa), one of the alpha-SFMe series surfactants, critical micellization concentration (CMC), solubility and degree of counterion binding (beta) were determined by means of electroconductivity measurements at different temperatures (at every 5 degrees C) ranging from 15 to 50 degrees C. The phase diagram of 14SFNa in pure water was constructed from the CMC- and solubility-temperature data, in which the Krafft temperature (critical solution temperature) was found around 0 degrees C. The changes in the Gibbs energy, Delta G(m)(0), enthalpy, Delta H-m(0), and entropy, Delta S-m(0), upon micelle formation as a function of temperature were evaluated taking beta values into calculation.