Investigation of Dynamical Heterogeneities in Polymer Melts

In this paper, dynamical heterogeneities are characterized both at the monomer and centre-of-mass level, in polymer melts well above their glass transition temperature, responsible for anomalous dynamics in these systems. Microscopic analysis of united atom molecular dynamics simulations of unentangled polyethylene melts suggests a molecular mechanism for the observed heterogeneous dynamics based on local density fluctuations about a tagged polymer. These local density fluctuations are related to variations in entropy in a small volume about a polymer in the melt, which result in initial connections of the dynamical heterogeneities to entropy.