Abstract: By means of oscillatory shear flow in the capillary, rheological experiments of aqueous solutions of quaternary ammonium Gemini surfactants containing methylene groups spacer(CH₂) s(referred to C_12-s-C₁₂·2Br, s=2,4,8) were carried out. By using dynamic light scattering method, the mean hydrodynamic radius(R h) of C_12-s-C₁₂·2Br micelles were measured to investigate the growth of C_12-s-C₁₂·2Br micelles. The aim of the experiments is to explore the effect of spacer chain length on the size and shape of micelles and the rheological property of the solution. The results show that the rheological property is mostly determined by the size and shape of micelles which depend on the spacer chain length of C_12-s-C₁₂·2Br. The rheological property of spherical and rodlike micelles solution is purely viscous, whereas the solution of threadlike micelles is viscoelastic. The viscosity of the solutions increases with the increase of NaBr concentration or the decrease of temperature.

Key words: Gemini surfactant, Rheological property, Dynamic light scattering