Growth of Irreversibly Adsorbed Layers and Corresponding Local Tg Perturbances in Polymer Nanocomposites*

Annealing a polymer system at temperatures above its Tg can induce the growth of an irreversibly adsorbed layer at the polymer-substrate interface which can impact the system’s bulk properties. Several efforts have been made to explore the implications of irreversibly adsorbed layer growth in thin films, however consideration has not yet been given to polymer nanocomposites, whose high processing temperatures and significant interfacial area may especially favor irreversible adsorption. Herein, we describe the local effects of irreversible adsorption in polystyrene-silica nanocomposites. By combining direct, local techniques such as fluorescence spectroscopy and TEM imaging, we elucidate the relationship between irreversibly adsorbed layer thickness and the corresponding local Tg perturbances, as well as how these parameters evolve with annealing time. The insights provided by this characterization of local interfacial dynamics may inform future endeavors towards the engineering of new and improved polymer nanocomposite materials.