Field-induced alignment of flexible polyelectrolytes in solution

Molecular dynamics simulations are used to study dynamical coupling between conformational fluctuations of a highly charged flexible macromolecule and its surrounding ionic cloud. We find that the basic model of a polyelectrolyte as a chain of charged monomers captures the main experimental findings on the field-induced alignment of polyelectrolytes despite its simplicity. Contrary to current theories, the correlated local charge and field fluctuations in the vicinity of the macromolecule are found to dominate alignment along an external field. We suggest that short-lived monomer-counterion clustering can be probed by measuring the field-induced anisotropy of x-ray and neutron scattering from polymer solutions.