Dynamics in Colloidal Liquids near a Crossing of Glass- and Gel-Transition Lines

TL;DR

This study uses mode-coupling theory to analyze the complex dynamics of colloidal liquids near the intersection of gel and glass transition lines, revealing how different arrest mechanisms and higher-order singularities influence particle motion.

Contribution

It provides a theoretical framework for understanding the interplay of gel and glass transitions in colloidal systems near a higher-order singularity.

Findings

Dynamics governed by hard-core repulsion and attraction-induced bonds.

Qualitative agreement with molecular-dynamics simulation results.

Interpretation of experimental correlation functions as gel-glass crossover.

Abstract

Within the mode-coupling theory for ideal glass-transitions, the mean-squared displacement and the correlation function for density fluctuations are evaluated for a colloidal liquid of particles interacting with a square-well potential for states near the crossing of the line for transitions to a gel with the line for transitions to a glass. It is demonstrated how the dynamics is ruled by the interplay of the mechanisms of arrest due to hard-core repulsion and due to attraction-induced bond formation as well as by a nearby higher-order glass-transition singularity. Application of the universal relaxation laws for the slow dynamics near glass-transition singularities explains the qualitative features of the calculated time dependence of the mean-squared displacement, which are in accord with the findings obtained in molecular-dynamics simulation studies by Zaccarelli et. al [Phys. Rev. E 66, 041402 (2002)]. Correlation functions found by photon-correlation spectroscopy in a micellar system by Mallamace et. al [Phys. Rev. Lett. 84, 5431 2000)] can be interpreted qualitatively as a crossover from gel to glass dynamics.