On the basis of the principle of Bratch`s electronegativity equalization, we calculated group partial charges and group electronegativities for nonionic surfactants with Pauling`s electronegativity parameters by using numerical calculation method. From calculated output, we have investigated structural stability of micelle, characteristics of hydrophilic and hydrophobic groups, and relation between CMC(Critical Micelle Concentraion) and group partial charge and group electronegativity of hydrophilic and hydrophobic groups for nonionic surfactants. We have known that CMC by micelle formation depends upon group partial charge and group electronegativity of hydrophilic and hydrophobic groups for surfactants. Also, the structural stability of micelle in H_2O solution is related to the electric double layer by the hydrophilic group of nonionic surfactants with H atoms in water. CMC is diminished by the decrease of repeating units in hydrophilic group at constant hydrophobic group and is diminished by the increments of alkyl chains in hydrophobic group at constant hydrophilic group for nonionic surfactants. In conclusion, CMC is diminished because there is no electrostatic repulsion and is diminished of Debye length by the increments of partial charge of hydrophobic group.

The effects of Ca^2+ ion on the formation of micelle colloid of nonionic surfactants, nonylphenol-(ethylene oxide)_n [NP-(EO)n; n=11,40,100) were investigated by the iodine solubilization method. The characteristics of spectra depended on the concentration of Ca^2+ ion and the number of EO unit. Above CMC(critical micelle concentration), the intensity of the CT (chargetransfer) band by the addition of Ca^2+ ion for the NP-(EO)_11 and NP-(EO)_40 increased and then decreased and for the NP-(EO)_100 continuously increased. The increase in the intensity of CT band were attributed to the compactness of micelle in the presence of Ca^2+ ion. These phenomena mad be explained by the fact that the linear ethylene oxide (EO) chain, relatively free to assume various configuration in aqueous solution, could form a pseudo-crown ether structures capable of forming complexes with Ca^2+ ion.