A Molecular Dynamics study of short-chain polyelectrolytes in explicit water: Toward the origin of ion-specific effects

We present all atom explicit water Molecular Dynamics simulation results for the structure of short (six monomer units) aliphatic ionenes in mixtures with a low-molecular weight electrolyte. The SPC/E model was used to describe water. Long-range effects were taken into account via the Ewald summation procedure. The results indicate that strongly hydrated ions such as F− cannot approach the nitrogen atom on the oligoion. In contrast, weakly hydrated I− ions accumulate close to the oligoion. These findings are consistent with the thermodynamic data and ongoing measurements of the dielectric relaxation in ionene solutions.