Chain dynamics in adsorbed polymer layers featuring strongly- and weakly-interacting polymer-substrate pairings

Though once conceptualized as "dead," adsorbed nanolayers of polymer atop a substrate are now recognized as capable of undergoing a glass transition, suggesting active local chain dynamics within this nanoscale region. While there exist a range of approaches for studying polymer dynamics, conventional characterization techniques such as calorimetry and ellipsometry are unsuitable for accessing high resolution information about the mobility within nanolayers adsorbed on a typical 2D substrate. Here, we leverage a combined characterization approach to report the respective dynamics of polystyrene and poly(methyl methacrylate) adsorbed on a silica surface. We investigate adsorption at the matrix-nanoparticle interface within a bulk nanocomposite system as a platform of study which, when combined with selective labeling, enables targeted local measurements of adsorbed layer properties via broadband dielectric spectroscopy, fluorescence spectroscopy, and transmission electron microscopy. Taken together, our findings contribute to a refined understanding of how chain dynamics are governed by underlying polymer-substrate interactions in adsorbed layers, affording new avenues towards intentional design of desirable material properties.