Segmental Dynamics of an Isolated Component Polymer Chain in Polymer Blends Near the Glass Transition

The segmental dynamics of a component chain isolated in its blending partner chains is examined using the reorientation of polymer-tethered fluorescent probes near the glass transition. It is found that the temperature dependence of the dynamics of an isolated component follows that of the other component, with a horizontal shift corresponding to the glass transition temperature modification, which may result from a local composition of approximate to 10% isolated component. On the contrary, the dynamic heterogeneity, another key dynamic feature near the glass transition, shows that the local dynamic environment of an isolated component becomes either as heterogeneous as a more inherently heterogeneous component or more heterogeneous than either. These observations emphasize that not only the chain connectivity but also the dynamic modulation of a component by the other component needs to be addressed in order to understand the segmental dynamics of an isolated component in polymer blends.