How Ultrasmall Nanoparticles Influence Polymer Dynamics in Different Length Scales

The addition of untethered polyhedral oligomeric silsesquioxane (POSS) fillers to a polymer matrix can significantly alter the motion of polymer chains and segments. In many instances, there are observed slowdowns in the segmental dynamics of the polymers, which seem to be independent of the overall chain dynamics. This leads to perplexing and inadequately explained variations in the glass transition temperature and terminal flow behavior based on the composition. To investigate the relaxation phenomena that could be responsible for this decoupling, we employed rheometry and dielectric relaxation spectroscopy (DRS) to examine material relaxations occurring near the onset of entanglement. An apparent relaxation emerges in the rheological response, regardless of the presence of entanglements in the polymer. A similar signal may also be detected in the DRS response. We will delve deeper into the significance of these relaxations in our discussion.