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Updated: Apr 3, 2026

Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films
Published on: January 26, 2016
Communication: Experimentally determined profile of local glass transition temperature across a glassy-rubbery
Roman R Baglay1, Connie B Roth1
1Department of Physics, Emory University, Atlanta, Georgia 30322, USA.
Abstract:
Studying the local glass transition temperature T(g) across a boundary, we investigate the characteristic length scales of cooperative dynamics. High molecular weight polymers have a large separation in time scales between cooperative segmental motion (α-relaxation) and chain diffusion allowing us to measure the local T(g)(z) profile across a glassy-rubbery interface of polystyrene/poly(n-butyl methacrylate) using fluorescence. We find this profile in cooperative dynamics does not correlate with the 7-nm wide symmetric composition profile of the interface, but instead is very broad, spanning 350-400 nm from one bulk T(g) value to another, and highly asymmetric, extending further into the glassy side.
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