DYNAMIC LIGHT-SCATTERING BY POLYELECTROLYTE SOLUTIONS

A generalized expression for the apparent diffusion coefficient (D(app)) for macroions as a function of scattering vector (q) is developed. Mathematica(R), a system of doing mathematics on a computer, was used to obtain the eigenvalues for a select set of polyion-electrolyte systems. It is shown that under the conditions of low electrolyte concentration D(app) exhibits a marked q-dependence. The second part of this communication focuses on the so-called ''ordinary-extraordinary'' transition observed in some polyelectrolyte systems. The characteristic D(app) versus electrolyte profile for this transition is compared with the 'splitting'' of relaxation times reported for many other polyelectrolyte systems. General problems associated with dynamic light scattering studies on macroion systems are discussed.