Polyelectrolyte electrophoresis: Field effects and hydrodynamic interactions

The dynamical and conformational properties of short polyelectrolytes are studied in salt-free solution exposed to an external electric field taking hydrodynamic interactions into account by a mesoscale simulation technique. As a function of polymer length, we find a non-monotonic electrophoretic mobility, in agreement with experiments, and diffusion coefficients, which are well described by the expression of rodlike objects, both aspects reflect the importance of hydrodynamic interactions. Strong electric fields lead to particular polymer conformations, which are illustrated in a schematic diagram.