Origin of dynamic heterogeneities in miscible polymer blends: A quasielastic neutron scattering study

In order to investigate the origin of the often invoked nanoheterogeneities in miscible polymer blends, we have performed quasielastic neutron scatter ing experiments on the component dynamics within the miscible polymer blend polyisoprene/polyvinyl ether including the pure components as a reference. We find that the apparent local heterogeneities observed by spectroscopic techniques originate from the chain specific crossover properties between e ntropy driven and local chain dynamics and are, thus, a purely dynamical ph enomenon.