By A. Menelle, 20/03/2015
Usually polyelectrolyte solutions present a peak in the polyion/polyion structure factor for some value q∗ of the momentum transfer (scattering vector). We describe a new regime in dense polymer solutions, typically above ~1mol/L, where q∗ is proportional to the concentration c of the solution. It is however not observed for all polyelectrolytes but only for those of intermediate stiffness, usually together with an ultimate regime where q∗ is proportional to √c and local orientational order prevails. This regime is robust against sample preparation and stable over time. We can understand it as jammed with randomly oriented persistent segments. This may explain why fully developed nematic order is so difficult to observe in synthetic polyelectrolytes.