Comparison of Ring and Linear Polyethylene from Molecular Dynamics Simulations

The conformational and dynamical properties of macromo-lecular melts are strongly affected by topological constraints. The extent to which the constraints become dominant depends on various polymer parameters, such as molecular weight and architecture. In this regard, the conformational characteristics and dynamics of linear polymers have been studied extensively experimentally and theoretically.1 It has been confirmed that their conformational properties in a melt are identical to those of unperturbed chains.2,3 With respect to their dynamics, a transition occurs from an isotropic motion, described by the Rouse model,1 to a locally anisotropic motion induced by the noncrossability of neighboring chains when the molecular weight exceeds a certain value. The latter dynamics may be ap-proximated by the reptation theoretical model,4 as confirmed by computer simulations5-7 and experiments.8-10 In the con-