Analysis of complex dielectric spectra. II: Evaluation of the activation energy landscape by differential sampling

Cooperative and non-cooperative dynamics in ultra-thin films of polystyrene studied by dielectric spectroscopy and capacitive dilatometry

“…The second term in Eq. (1) accounts for ohmic conduction, more details about the fit procedure for dielectric data are given in [30,31]. The relaxation time data for the 285 nm thick PS sample, obtained in this way, are plotted in the activation diagram, Fig.…”

“…The other parameters R and s 1 have the usual meaning. For the thinnest film (L = 8.7 nm), a two-dimensional fit procedure of the e 00 (f, T) data to a combined HN-VFT-function [30,31] was applied that yielded the VFT-parameters (rightmost solid line in Fig. 4) in a direct way.…”

Glass transition and chain mobility in thin polymer films

“…T g was identified as the temperature at which s max a was equal to 100 s. The multilayer film geometry has also been used recently in dielectric relaxation studies of polymer trilayer films consisting of a dielectrically active layer (i-PMMA) sandwiched between two layers of a different polymer (PS) [42]. T g values for the i-PMMA layers were determined by applying an activation energy fine-structure analysis [43] to the dielectric data. A slight increase in T g with decreasing i-PMMA film thickness was observed, which is qualitatively different from the decrease in T g with decreasing film thickness observed for the same i-PMMA films in contact with the metallic electrodes.…”

Dielectric spectroscopy on aging glasses

“…While there are numerous recent reports on physical aging in spin glasses [ 6] and polymers [ 5,7,8,9], much fewer experiments were performed on canonical glass formers. Especially, having in mind that dielectric spectroscopy has proven a key technique for the study of glassy dynamics in equilibrium, it is a stonishing that investigations of glassy non-equilibrium dynamics in low molecularweight glass formers with this technique are relatively scarce [3,10,11,12].…”