Spatial gradient of the dynamics of capped thin polymer films through broadband dielectric spectroscopy

Near-interface polymers exhibit distinct dynamics from polymers far away from the interface, leading to a dynamics gradient at nanometer vicinity at the interface. The characteristics of the dynamics gradient have been taken as a key to reveal the interface effect. However, the details of the spatial gradient of polymer dynamics at the interface remains a challenge in experiments. In this contribution, we analyze the interfacial dynamics of capped thin polymer film through our newly developed analysis of broadband dielectric measurements, the continuous Havriliak-Negami (HN) function model, which can quantify the spatial gradient of the interface dynamics. Polymer films with different chemistry and different thicknesses down to less than 10 nm have been studied and analyzed. We will also discuss the comparison between the experimental observations and the leading theoretical approaches on the interface dynamics.