Abstract
We report on the structure and dynamics of model mono-, di-, and
tri-omega-functionalized three-arm star polybutadiene melts. By using
x-ray scattering and dynamic rheological measurements, we find that
functionalization of the arm ends can lead to distinctly different
supramolecular structures and material behavior. The monofunctionalized
samples behave like multiarm nonionic star-like dendrimers, whereas the
difunctional stars resemble a transient network consisting of highly
branched structures with a very broad relaxation spectrum. On the other
hand, the trifunctional stars seem to develop an unusually regular
structure of dominant intramolecularly aggregated functional groups
leading to collapsed star conformations, resembling soft spheres, and a
well-defined terminal relaxation. These results suggest that by
tailoring the telechelic functionalization of regular star polymers, a
route to design and obtain a wealth of controlled supramolecular
structures exhibiting a rich and variable dynamics could open. (C) 1999
American Institute of Physics. [S0021-9606(99)51528-6].