Surface mobility gradient and emergent facilitation in glassy films.
basic_science · Level V
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- Record sourced from PubMed, PMID 38757511.
- Also identified by DOI 10.1039/d4sm00221k.
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Abstract
Confining glassy polymers into films can substantially modify their local and film-averaged properties. We present a lattice model of film geometry with void-mediated facilitation behaviors but free from any elasticity effect. We analyze the spatially varying viscosity to delineate the transport properties of glassy films. The film mobility measurements reported by Yang <i>et al.</i>, <i>Science</i>, 2010, <b>328</b>, 1676 are successfully reproduced. The flow exhibits a crossover from a simple viscous flow to a surface-dominated regime as the temperature decreases. The propagation of a highly mobile front induced by the free surface is visualized in real space. Our approach provides a microscopic treatment of the observed glassy phenomena.