The problem of bimodal distributions in dynamic light scattering: Theory and experiment

A new method is proposed for analyzing the results of dynamic light scattering measurements of polymer solutions containing macromolecules with substantially different molecular masses. The processing algorithm makes it possible to correctly allow for effects of the quality of solvent and the conformation and polarizability of macromolecules on the contributions of components of a system to the intensity of scattering. The developed method is tested for a model mixture of two polystyrene samples dissolved in a good solvent (tetrahydrofurane) and a θ solvent (cyclohexane) and is applied to study a system containing a linear polymer and an interpolymer complex.