EFFECT OF HYDROPHOBIC CHAIN-LENGTH OF SURFACTANTS ON ENTHALPY-ENTROPYCOMPENSATION OF MICELLIZATION

It is well-known that there exists a minimum critical micelle concentr ation (cmc) in the cmc-temperature curve. It is found that the tempera ture of minimum cmc, T-min, for both nonionic and ionic surfactants in creases as the hydrophobicity of surfactants decreases. The temperatur e dependence of cme is used to calculate the enthalpies and entropies of micelle formation for six different homologous series of surfactant s, The enthalpy-entropy compensation plot exhibits an excellent linear ity. It is found that all the compensation lines for surfactants in a homologous series an parallel to one another and the intercept of thes e compensation lines is a linear function of the hydrophobic chain len gth of surfactants.