Glasslike Arrest in Spinodal Decomposition as a Route to Colloidal Gelation

TL;DR

This paper demonstrates that colloidal gelation via spinodal decomposition is driven by a glass transition in colloid-rich regions, with dynamics well-described by mode coupling theory using full static structure input.

Contribution

It reveals that gelation results from a glass transition in colloid-rich regions during spinodal decomposition, providing a theoretical framework for understanding gel formation.

Findings

Gelation occurs when colloid-rich regions undergo a glass transition.

The characteristic length scale decreases with deeper quenches.

Mode coupling theory accurately describes the dynamics when using full static structure.

Abstract

Colloid-polymer mixtures can undergo spinodal decomposition into colloid-rich and colloid-poor regions. Gelation results when interconnected colloid-rich regions solidify. We show that this occurs when these regions undergo a glass transition, leading to dynamic arrest of the spinodal decomposition. The characteristic length scale of the gel decreases with increasing quench depth, and the nonergodicity parameter exhibits a pronounced dependence on scattering vector. Mode coupling theory gives a good description of the dynamics, provided we use the full static structure as input.