  We investigate electro-osmosis in aqueous solutions of polyelectrolytes using
mean-field equations. A solution of positively charged polyelectrolytes is
confined between two negatively charged planar surfaces, and an electric field
is applied parallel to the surfaces. When electrostatic attraction between the
polymer and the surface is strong, the polymers adhere to the surface, forming
a highly viscous adsorption layer that greatly suppresses the electro-osmosis.
Conversely, electro-osmosis is enhanced by depleting the polymers from the
surfaces. We also found that the electro-osmotic flow is invertible when the
electrostatic potential decays to its bulk value with the opposite sign. These
behaviors are well explained by a simple mathematical form of the
electro-osmotic coefficient.
