Molecular dynamics of ions in two forms of an electroactive polymer.

Molecular dynamics (MD) are performed in all-atom simulations of two polymer species based on polythiophene. In one case the amphiphilic polymer forms a monolayer interface between a vacuum and an aqueous layer containing ions. The electroactive nature of the polymer is invoked by conferring a negative charge on it to compensate for charge imbalance in the Na(+) and Cl(-) concentrations of the aqueous layer. The effects of hydrostatic pressure and charge imbalance on the stability of the monolayer are investigated. In another simulation a polythiophene oligomer is wound into a helix where it serves as an ion channel between two aqueous regions on both sides of a phospholipid bilayer membrane.