Polymer dynamics from large to small scales

This lecture reviews quasielastic small-angle neutron scattering experiments exploring the dynamics of polymer melts. Starting from the entropy driven Rouse dynamics, I address its limitation to larger and smaller scales. On the large scale side neutron spin echo spectroscopy reveals the single chain dynamic structure factor and the self correlation function of a spatially confined chain in accordance with the reptation concept and shows that contour length fluctuations limit the chain confinement on the time scale of local reptation. Towards shorter distances it is shown that intrachain dissipation processes are the leading mechanism limiting Rouse motion.