%0 Journal Article %T On the bridge hypothesis in the glass transition of freestanding polymer films %+ Gulliver (UMR 7083) %+ Tel Aviv University (TAU) %+ University of Toronto, Toronto %+ University of Waterloo [Waterloo] %+ Laboratoire Ondes et Matière d'Aquitaine (LOMA) %A Bonneau, Haggai %A Arutkin, Maxence %A Chen, Rainni %A Forrest, James, A %A Raphael, Elie %A Salez, Thomas %@ 1292-8941 %J European Physical Journal E: Soft matter and biological physics %I EDP Sciences: EPJ %V 46 %P 8 %8 2023 %D 2023 %Z 2212.04296 %Z Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft] %Z Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] %Z Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech] %Z Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] %Z Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph] %Z Physics [physics]/Mechanics [physics]/Solid mechanics [physics.class-ph] %Z Physics [physics]/Physics [physics]/Fluid Dynamics [physics.flu-dyn]Journal articles %X Freestanding thin polymer films with high molecular weights exhibit an anomalous decrease in the glass-transition temperature with film thickness. Specifically, in such materials, the measured glass-transition temperature evolves in an affine way with the film thickness, with a slope that weakly depends on the molecular weight. De Gennes proposed a sliding mechanism as the hypothetical dominant relaxation process in these systems, where stress kinks could propagate in a reptation-like fashion through so called bridges, i.e. from one free interface to the other along the backbones of polymer macromolecules. Here, by considering the exact statistics of finite-sized random walks within a confined box, we investigate in details the bridge hypothesis. We show that the sliding mechanism cannot reproduce the basic features appearing in the experiments, and we exhibit the fundamental reasons behind such a fact. %G English %2 https://cnrs.hal.science/hal-03889405/document %2 https://cnrs.hal.science/hal-03889405/file/Bonneau2022.pdf %L hal-03889405 %U https://cnrs.hal.science/hal-03889405 %~ ESPCI %~ CNRS %~ PARISTECH %~ OPENAIRE %~ GULLIVER %~ LOMA %~ INC-CNRS %~ PSL %~ ESPCI-PSL %~ ANR %~ TEST2-HALCNRS