Abstract: The method of conductivity was employed to determine the ionizability of the DTAB micelle and Gemini surfactants micelle and the method of dynamic lighting scatter was used to determine the diffusing coefficients of surfactants micelles. According to the DLVO theory, we discussed the influence of the spacer length and ionic strength on the intermicellar interactions. The results show that spacers have influence on the ionizability and density of charge of the micelles, and then affect the intermicellar interactions. The degree of the influence depends on the ability of attracting electrons of spacers and the charge′s overlapping degree of the two headgroups in the Gemini surfactants. The influence on the intermicellar interactions which was caused by ionic strength can be divided into two aspects: at a low ionic strength, the net intermicellar interactions is repulsive, and it is unfavorable to the growth of micelles; but at a high ionic strength, the net intermicellar interactions is attractive, and it is favorable to the growth of micelles.

Key words: Gemini surfactants, Intermicellar interaction, Dynamic lighting scatter, Ionizability