Mode-coupling theory for the slow collective dynamics of fluids adsorbed in disordered porous media

TL;DR

This paper develops a mode-coupling theory to describe the slow dynamics and glass transition phenomena of fluids confined in disordered porous media, revealing complex transition scenarios and a reentry phenomenon.

Contribution

It introduces a modified mode-coupling theory with a linear memory kernel term for fluids in disordered porous media, providing new insights into their glass transition behavior.

Findings

Prediction of continuous and discontinuous glass transitions

Identification of higher-order singularities and glass-glass transitions

Reentry phenomenon indicating competition between fluid-fluid and fluid-matrix interactions

Abstract

We derive a mode-coupling theory for the slow dynamics of fluids confined in disordered porous media represented by spherical particles randomly placed in space. Its equations display the usual nonlinear structure met in this theoretical framework, except for a linear contribution to the memory kernel which adds to the usual quadratic term. The coupling coefficients involve structural quantities which are specific of fluids evolving in random environments and have expressions which are consistent with those found in related problems. Numerical solutions for two simple models with pure hard core interactions lead to the prediction of a variety of glass transition scenarios, which are either continuous or discontinuous and include the possibility of higher-order singularities and glass-glass transitions. The main features of the dynamics in the two most generic cases are reviewed and illustrated with detailed computations. Moreover, a reentry phenomenon is predicted in the low fluid-high matrix density regime and is interpreted as the signature of a decorrelation mechanism by fluid-fluid collisions competing with the localization effect of the solid matrix.