Investigation of polymer behavior confined in the heterogeneous environment using a 2-dimensional model nanocomposite*

Polymer nanocomposites with heterogeneous interfaces in the vicinity of inorganic nanofillers have attracted broad interest due to their functionality. One important finding was that when there exists a large dynamic asymmetry at the interface, nanocomposite may display thermal stiffening. In the current work, a 2-dimensional model nanocomposite is adopted to help understand local thermal properties and dynamics at the heterogeneous interface. The planar model nanocomposite has a sandwich structure, where the top layer is polyethylene oxide (PEO), the middle layer is a high-glass-transition-temperature polymer (such as poly(methyl methacrylate), polycarbonate, poly(2–vinyl pyridine), or polystyrene), and the bottom layer is a silica substrate. Degradation and local glass transition behavior were characterized by Thermogravimetric Analysis (TGA) and Modulated Differential Scanning Calorimetry (MDSC), respectively. Segmental and local relaxation along with cooperativity were characterized by Broadband Dielectric Spectroscopy (BDS). The results affirmed the capability of these techniques in retrieving information from multilayered thin film samples and revealed how polymer chains behave when confined in a heterogeneous environment.