Percolation of Immobile Domains in Supercooled Thin Polymeric Films

TL;DR

This study investigates how immobile regions in supercooled thin polymer films form and percolate near the glass transition, revealing surface effects and supporting a recent theoretical model.

Contribution

It provides the first molecular dynamics simulation evidence of percolating immobile domains in thin polymer films near the glass transition.

Findings

Immobile domains decrease with distance from the surface.

Percolation occurs perpendicular to the surface near the glass transition.

Results support a recent theoretical model of glass transition.

Abstract

We present an analysis of heterogeneous dynamics in molecular dynamics simulations of a thin polymeric film, supported by an absorbing structured surface. Near the glass transition "immobile" domains occur throughout the film, yet the probability of their occurrence decreasing with larger distance from the surface. Still, enough immobile domains are located near the free surface to cause them to percolate in the direction perpendicular to surface, at a temperature near the glass transition temperature. This result is in agreement with a recent theoretical model of glass transition.