Cooperative strings and glassy dynamics in various confined geometries

TL;DR

This paper extends a cooperative string model to study glass transition and surface mobility in various confined geometries, including effects of attractive substrates, providing insights into confined supercooled liquids.

Contribution

It introduces a unified model for different geometries and incorporates attractive substrate effects, advancing understanding of confinement on glassy dynamics.

Findings

Effective glass transition varies with geometry and substrate interactions.

Surface mobility is enhanced near free interfaces.

Attractive substrates significantly influence relaxation dynamics.

Abstract

Previously, we developed a minimal model based on random cooperative strings for the relaxation of supercooled liquids in the bulk and near free interfaces, and we recovered some key experimental observations. In this article, after recalling the main ingredients of the cooperative string model, we study the effective glass transition and surface mobility of various experimentally-relevant confined geometries: freestanding films, supported films, spherical particles, and cylindrical particles, with free interfaces and/or passive substrates. Finally, we introduce a novel way to account for a purely attractive substrate, and explore the impact of the latter in the previous geometries.