We probe the structure-dynamics relationship in melts of star polymers with
high functionality using small-angle X-ray scattering, rheology, and Monte
Carlo computer simulations. These materials represent model steric soft sp
heres, which order in a liquidlike structure on a macromolecular scale beca
use of the impenetrability of the cores. This is a consequence of the compl
ex star topology, which is characterized by an inhomogeneous intrastar mono
mer density distribution. The signature of the structure appeares in the dy
namics of these systems as a slow terminal relaxation process, in addition
to the classical faster arm retraction mechanism. The slow process is attri
buted to the structural rearrangements of the stars within their liquidlike
order and can be thought of as a reflection of their colloidal nature. We
identify the dependence of this dynamic mode on the molecular parameters, i
.e., star functionality and arm size.