Short-time relaxation at polymeric interfaces

The interdiffusion of long polymer chains at the interface of two melts has been studied as a function of time by neutron reflection. The time range studied spanned from the time characteristic of the motion of the single segment (Rouse time, e) up to the time at which the center of mass of the whole molecule has moved a radius of gyration (reptation time). At least for t> e, the diffusion rate slows down with time until the bulk diffusion rate is reached, in agreement with the current theories for the motion of a polymeric chain in a melt. © 1990 The American Physical Society.