Polymer Dynamics in Poly(styrene-isoprene-2,vinylpyridine) miktoarm terpolymers*

In this study we employ broadband dielectric spectroscopy to probe the motion of several poly(styrene-isoprene-2,vinylpyridine) (PS-PI-P2VP, respectively) miktoarm star terpolymers with constant “PS” and “PI” block molecular weights, and we vary the molecular weight of the “P2VP” block. A strong but significantly faster secondary, dipolar relaxation is observed over wide temperature and frequency ranges for the terpolymers compared to homopolymers. This process is attributed to local dynamics of the “P2VP” heterocyclic segments. Additionally, to probe the end-to-end dipole vector timescales of the Type-A polymer chains in the “PI” block, lithium salts were added to suppress the β-process of the “P2VP” block due to coordination of the nitrogen in the heterocycle with the Li+ cation. These data for the “PI” chain relaxation are compared the dynamics of poly(isoprene) in phase separated linear diblock and homopolymer systems. We show that this unique miktoarm star architecture greatly affects the dynamics in these polymers, and discuss the results in terms of polymer dynamics in well-studied phase separated systems.