Molecular dynamics study of polymer conformation as a function of concentration and solvent quality.

A coarse-grained model for molecular dynamics simulations of polymer solutions with variable solvent quality is proposed. This model allows solvent quality to be varied over the whole range from very poor to very good solvent conditions by varying a single parameter. The model has several advantages. All interactions are short ranged and repulsive, making the model very computationally efficient compared with other explicit solvent models that include the long-ranged attractive part of the interactions; the solvent is included explicitly, ensuring that the theta condition corresponds to a genuine cancellation of the solvent-mediated polymer-polymer interactions; and hydrodynamic interactions and entanglement can occur for all solvent conditions. The theta point is determined and the conformational properties of a 50-bead chain system are investigated over the whole concentration range from the dilute limit to the melt as a function of solvent quality.