Scaling of near-interface dynamics resolved through broadband dielectric spectroscopy with a designed dielectric marker system

Polymers at the interface can exhibit profound alterations in dynamics and mechanical properties compared with the bulk. However, deficiencies in the quantification of gradients of interfacial dynamics impose grand challenges and generate much confusion in the understanding of interfacial dynamics and their connection with the bulk glass transition. In this work, we demonstrate a new dielectric marker system that can be precisely positioned at distance on the order of away from the interface. Broadband dielectric spectroscopy (BDS) is employed to quantify the structural relaxation of the dielectric marker, which reflects salient features of the interfacial dynamics. The ratio of the structural relaxation of the dielectric marker, τ_d, and the segmental dynamics of polymers away from the interface, τ_b, follows a power law of τ_d/τ_b ~ τ_b^-0.1 over a wide range of temperatures before a deviation is observed at low temperatures approaching the glass transition temperature of the polymer. Implications of the power law observation will be discussed in the presentation.