Scaling between Structural Relaxation and Particle Caging in a Model Colloidal Gel

TL;DR

This study reveals that a universal scaling relation between particle caging and structural relaxation, known in dense glasses, also applies to low-density colloidal gels, highlighting fundamental aspects of glassy dynamics.

Contribution

It demonstrates that the same scaling between relaxation time and localization length applies to colloidal gels, extending the universality of glassy dynamics to different systems.

Findings

Scaling relation holds in colloidal gels at low density.

Strong coupling between network rearrangements and particle localization.

Scaling captures fundamental physical elements of glassy behavior.

Abstract

In polymers melts and supercooled liquids, the glassy dynamics is characterized by the rattling of monomers or particles in the cage formed by their neighbors. Recently, a direct correlation in such systems, described by a universal scaling form, has been established between the rattling amplitude and the structural relaxation time. In this paper we analyze the glassy dynamics emerging from the formation of a persistent network in a model colloidal gel at very low density. The structural relaxation time of the gel network is compared with the mean squared displacement at short times, corresponding to the localization length associated to the presence of energetic bonds. Interestingly, we find that the same type of scaling as for the dense glassy systems holds. Our findings well elucidate the strong coupling between the cooperative rearrangements of the gel network and the single particle localization in the structure. Our results further indicate that the scaling captures indeed fundamental physical elements of glassy dynamics.