Effect of solvent quality on the conformation and relaxation of polymers via dissipative particle dynamics

Dissipative particle dynamics (DPD), a new simulation technique appropriate at mesoscopic length scales, has been applied to a dilute solution of polymer in solvents of varying quality. Unlike earlier simulations, the solvent is represented in the form mobile particulate packets, so that potential interferences of solvent flow about neighboring beads of the polymer are explicitly included. We establish that the mechanism used to vary the solvent quality produces a collapse transition, as judged both by static conformational and by dynamical criteria. The scaling of the polymer radius of gyration and of its longest dynamical relaxation time are in good agreement with accepted theory. The condition for transition from good to poor solvent is consistently predicted by several static and dynamical measures. Though the model that underlies DPD is not atomically detailed, the results presented strongly suggest that both excluded volume and hydrodynamic interaction must present.