Slow dynamics, aging, and glassy rheology in soft and living matter

TL;DR

This paper reviews the origins of slow dynamics, aging, and glassy rheology in soft and living matter, discussing theoretical models, experimental results, and recent advances in understanding these complex behaviors.

Contribution

It provides a comprehensive overview of theoretical frameworks and experimental findings related to slow dynamics, aging, and rheology in soft and living materials, highlighting recent progress.

Findings

Structural rearrangements explain slow dynamics and aging.

The Soft Glassy Rheology model predicts aging behavior.

XPCS experiments reveal aging in clay suspensions.

Abstract

We explore the origins of slow dynamics, aging and glassy rheology in soft and living matter. Non-diffusive slow dynamics and aging in materials characterised by crowding of the constituents can be explained in terms of structural rearrangement or remodelling events that occur within the jammed state. In this context, we introduce the jamming phase diagram proposed by Liu and Nagel to understand the ergodic-nonergodic transition in these systems, and discuss recent theoretical attempts to explain the unusual, faster-than-exponential dynamical structure factors observed in jammed soft materials. We next focus on the anomalous rheology (flow and deformation behaviour) ubiquitous in soft matter characterised by metastability and structural disorder, and refer to the Soft Glassy Rheology (SGR) model that quantifies the mechanical response of these systems and predicts aging under suitable conditions. As part of a survey of experimental work related to these issues, we present x-ray photon correlation spectroscopy (XPCS) results of the aging of laponite clay suspensions following rejuvenation. We conclude by exploring the scientific literature for recent theoretical advances in the understanding of these models and for experimental investigations aimed at testing their predictions.