The Stokes-Einstein Relation in Supercooled Aqueous Solutions of Glycerol

TL;DR

This study investigates how adding water to glycerol affects the validity of the Stokes-Einstein relation near the glass transition, finding that water restores the relation and delays frustration domain formation.

Contribution

It demonstrates that increasing water concentration in glycerol-water mixtures restores the Stokes-Einstein relation near the glass transition, providing insights into molecular dynamics in supercooled solutions.

Findings

Stokes-Einstein relation breaks down near glass transition in pure glycerol.

Adding water restores the relation in glycerol-water mixtures.

Water delays the formation of frustration domains.

Abstract

The diffusion of glycerol molecules decreases with decreasing temperature as its viscosity increases in a manner simply described by the Stokes-Einstein(SE) relation. Approaching the glass transition, this relation breaks down as it does with a number of other pure liquid glass formers. We have measured the diffusion coefficient for binary mixtures of glycerol and water and find that the Stokes-Einstein relation is restored with increasing water concentration. Our comparison with theory suggests that addition of water postpones the formation of frustration domains