Linear dynamics of end-functionalized polymer melts: linear chains, stars, and blends

We investigated the linear viscoelastic response of model mono-, di-, and tri-ω-functionalized three-arm star polybutadiene melts with zwitterionic end groups using dynamic rheological measurements. Depending on the degree of functionalization, these polymers self-assembled into distinct supramolecular structures resembling nonspherical starlike objects, transient networks consisting of highly branched structures, and collapsed soft-sphere conformations, with aggregation numbers affected by the arm molecular weight. The dependence of the relaxation times on the latter indicated activated processes analogous to multiarm star polymers. On the other hand, the dynamics of ω-functionalized linear chains, forming clusters with tubular or bcc structures, was characterized by a much smaller energetic barrier. The use of different sample preparation protocols as well as binary blends involving stars demonstrated the stability of the self-organized structures and confirmed the assignment of the relaxation processes.