Effect of Polymer Topology on Microstructure and Dynamics in Polymer Blends

Structure and dynamics of miscible polymer blends have been extensively studied for linear chains in the past. In this work, we used poly(ethylene oxide)-poly(methyl methacrylate) blend system with varying polyethylene oxide architectures (linear, stars, hyper-branched and bottlebrushes) and compositions to explore the effects chain topology on miscibility, glass transition and segmental dynamics of the blend components. XRD results suggest that room temperature miscibility of these polymers can be extended by using compact star shaped polyethylene oxide instead of linear chains that crystallize above 35%. Temperature modulated DSC results showed two distinct glass transitions in intermediate compositions for all systems. The T_g results suggest the possibility to access a previously-unexplored intermediate regime between the conventional linear blends and nanocomposites with hard fillers. Finally, neutron backscattering and broadband dielectric spectroscopy studies unveil a non-monotonic dependence of segmental dynamics on the polymer compactness.