Rheological properties of quaternary ammonium Gemini surfactants in aqueous solutions

By means of oscillatory shear flow in the capillary, rheological experiments of aqueous solutions of quaternary ammonium Gemini surfactants containing methylene groups spacer (CH2),(referred to C-12-s-C-12 . 2Br, s = 2,4,8) were carried out. By using dynamic light scattering method, the mean hydrodynamic radius(Rh) of C-12-s-C-12 . 2Br micelles were measured to investigate the growth of C-12-s-C-12 . 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-C-12 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.