Nanoparticle Motion in Entangled Melts of Linear and Nonconcatenated Ring Polymers

The motion of nanoparticles (NPs) in entangled melts of linear polymers and nonconcatenated ring polymers are compared by large-scale molecular dynamics simulations. The comparison provides a paradigm for the effects of polymer architecture on the dynamical coupling between NPs and polymers in nanocomposites. Strongly suppressed motion of NPs with diameter <i>d</i> larger than the entanglement spacing <i>a</i> is observed in a melt of linear polymers before the onset of Fickian NP diffusion. This strong suppression of NP motion occurs progressively as <i>d</i> exceeds <i>a</i> and is related to the hopping diffusion of NPs in the entanglement network. In contrast to the NP motion in linear polymers, the motion of NPs with <i>d</i> > <i>a</i> in ring polymers is not as strongly suppressed prior to Fickian diffusion. The diffusion coefficient <i>D</i> decreases with increasing <i>d</i> much slower in entangled rings than in entangled linear chains. NP motion in entangled nonconcatenated ring polymers is understood through a scaling analysis of the coupling between NP motion and the self-similar entangled dynamics of ring polymers