DYNAMICS OF COMPLEX FLUIDS STUDIED BY COMPLEX ELECTROPHORETIC SPECTROSCOPY

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Biopolymers and colloids are charged in aqueous solutions and show translational motion under electric field (electrophoresis). The electrophoresis is widely used for fractionation and analysis of biopolymers such as DNA and proteins. The electrophoretic mobility defined as the ratio of velocity to applied field is one of characteristic quantity of colloids and many technical methods have been developed to measure dc mobility. If the measurement of dynamics complex mobility is available, we can obtain rich information on electrokinetics of colloids. But such kind of studied have not been realized until now. In this research, we have developed new method to measure complex dynamic electrophoretic mobility hi wide frequency range by using dynamics light scattering. By this method, we have succeeded in measuring dynamics mobility between 1Hz to 100kHz for the first time in the world. Rich information on counter ions surrounding colloids can be obtained from this study. Since electrophoretic mobility is proportional to inverse of viscosity of solvent, the local structure and local mechanical properties of complex fluids can be obtained from dynamic mobility of a particles embedded in them. In this study, we have studied dynamics mobility of nano-sized colloidal particles dispersed in lamellar phase of nonionic surfactants and found hierarchical dynamics in lamellar phase produced by its nano-scaled hierarchical structure.