| Popis: |
The Molecular Dynamics Simulation technique has been used to describe the behavior of the polypyrrole/water interface at two different oxidation states: neutral (or reduced) and charged (or oxidized) polypyrrole state. The system was modeled by two symmetric and amorphous polymer layers, each one containing 64 polypyrrole chains with 10 monomeric units per chain and 2677 water molecules. When the oxidized polypyrrole was modeled, 128 chloride ions used as counterions to balance the excess of charge of the oxidized polypyrrole. From the simulated trajectories, several properties with atomic detail have been evaluated such as volume changes during oxidation or reduction process, the atomic and charge distribution profile across the polypyrrole/water interface, and the transitional diffusion coefficient and dehydration of chlorine ions from bulk water to the interior of the polymer matrix. In this sense, a diminution of the hydration and translational diffusion coefficient was obtained for the chloride ions when they penetrated into the polymer matrix. |
