Studies on Diffusion of Surfactants and Macromolecules

Doktorsavhandling, 1993

A new apparatus for measuring the translational diffusion coefficient in liquids at steady state is presented. The advantages of the described technique are i. the ability to characterize the dependence of the diffusion coefficient on concentration with a single experiment, and ii. simplified transport equation since the time dependence is absent, thus making the apparatus suitable for studying complex systems. The apparatus is used to determine the diffusion coefficient of sodium dodecyl sulfate below and slightly above the CMC. Surfactant diffusion is also analyzed theoretically by means of non- equilibrium thermodynamics. The rotational diffusion coefficient of rod like colloidal molecules is determined using static light scattering while dynamic light scattering (DLS) is used to determine the diffusion coefficient of W/O microemulsion systems and their corresponding size and interparticle interactions.