Counterion Distribution of Model Polyelectrolytes Studied by Anomalous Small-Angle X-ray Scattering

The most important biopolymers like DNA, proteins and polysaccharides are polyelectrolytes and polyelectrolytes are widely found in applications. The complex properties of these molecules have been studied for a long time. Polyelectrolyte solutions show „special effects “ like the increase of the reduced viscosity upon dilution, the fomation of strongly ordered domains coexisting with voids and the splitting of the ordinary diffusion coefficient into two diffusion processes above a certain polymer and below a certain added salt concentration. [1] In contrast to uncharged polymers, polyelectrolytes are still far from beeing understood and the nature of the mentioned effects is still being discussed. The reason for many questions being still open is a complex interplay of conformational and interaction effects. For fundamental phenomena it is not clear whether they are due to conformational changes or interaction effects. With this motivation we study polyelectrolytes with a fixed geometry or decreased flexibility as model systems. Recently, polyelectrolyte microgels, small spherical polyelectrolyte networks served as a model system to investigate intermolecular interaction. It could be shown by light scattering experiments that the formation of structured domains is due to a long-range attractive force that is electrostatic in nature. [2,3] Obviously certain effects that are not considered in