Local elastic response measured near the colloidal glass transition.

  title={Local elastic response measured near the colloidal glass transition.},
  author={D. Anderson and David Schaar and Hilary G. E. Hentschel and J. C. Van Hay and Piotr Habdas and Eric R. Weeks},
  journal={The Journal of chemical physics},
  volume={138 12},
We examine the response of a dense colloidal suspension to a local force applied by a small magnetic bead. For small forces, we find a linear relationship between the force and the displacement, suggesting the medium is elastic, even though our colloidal samples macroscopically behave as fluids. We interpret this as a measure of the strength of colloidal caging, reflecting the proximity of the samples' volume fractions to the colloidal glass transition. The strain field of the colloidal… 

Figures and Tables from this paper

Active microrheology of soft particle glasses
We study the forced motion of a tagged soft particle through a jammed suspension of identical soft particles using particle simulations. We relate the local particle dynamics, microstructure, and
Active microrheology of colloidal suspensions: simulation and microstructural theory
Accelerated Stokesian Dynamics (ASD) simulation and a microstructural theory are applied to study structure and the viscosity of hard-sphere Brownian suspensions in active microrheology (MR).We
Trajectories of probe spheres in generalized linear viscoelastic complex fluids.
A coupled harmonically bound Brownian particle (c-HBBP) model is introduced, in which the relaxation modes of the viscoelastic medium are treated as harmonic wells, and the resulting mean square displacements predicted are consistent with the single-particle generalized Stokes-Einstein relation of linear passive microrheology.
Elastically cooperative activated barrier hopping theory of relaxation in viscous fluids. I. General formulation and application to hard sphere fluids.
The present work provides a foundation for constructing a quasi-universal, fit-parameter-free theory for relaxation in thermal molecular liquids over 14 orders of magnitude in time.
Yield stress "in a flash": investigation of nonlinearity and yielding in soft materials with an optofluidic microrheometer.
An optofluidic microrheometer is used, based on the scattering of an infrared beam onto a microbead, to investigate the conditions for a transition at the microscale, determining the limits of linear response and yield stress values, and observing quantitative agreement with bulk measurements.
Microrheology of colloidal systems.
T theoretical models available in the literature for both passive and active microrheology are discussed, focusing on the case of single-probe motion in model colloidal host media and some unexpected features, such as superdiffusive motion of the probe related to the breaking of nearest-neighbor cages.
Active microrheology in two-dimensional magnetic networks.
The diffusion dynamics of the tracer particles are anisotropic with superdiffusive behavior in force direction, and this transport anomaly is investigated via van Hove correlation functions and residence time distributions.
Figures and Supplymentary Videos for "Anatomy of cage formation in a 2D glass-forming liquid"
The solidity of glassy materials is believed to be due to the cage formed around each particle by its neighbors, but in reality the details of cage-formation remain elusive [1–4]. This cage starts to


Forced motion of a probe particle near the colloidal glass transition
We use confocal microscopy to study the motion of a magnetic bead in a dense colloidal suspension, near the colloidal glass transition volume fraction g. For dense liquid-like samples near g, below a
Inhomogeneous elastic response of silica glass.
The existence of a length scale xi characterizing the correlations of this field is demonstrated, and the "boson-peak" anomaly of the density of states can be traced back in both cases to elastic inhomogeneities on wavelengths smaller than xi where classical continuum elasticity becomes simply unapplicable.
Local elasticity map and plasticity in a model Lennard-Jones glass.
This work calculates the local elastic moduli in a weakly polydispersed two-dimensional Lennard-Jones glass undergoing a quasistatic shear deformation at zero temperature and shows that zones of low shear modulus concentrate most of the strain in the form of plastic rearrangements.
A simple paradigm for active and nonlinear microrheology
In microrheology, elastic and viscous moduli are obtained from measurements of the fluctuating thermal motion of embedded colloidal probes. In such experiments, the probe motion is passive and
Probability Densities of a Forced Probe Particle in Glass: Results from Mode Coupling Theory and Simulations of Active Microrheology
Abstract We investigate the displacements of a probe particle inside a glass, when a strong external force is applied to the probe (active nonlinear microrheology). Calculations within mode coupling
Active microrheology of a colloidal suspension in the direct collision limit
The single-point active nonlinear microrheology of a colloidal suspension is measured using laser tweezers in the limit that the diameter of the probe particle approaches the diameter of the bath
The physics of the colloidal glass transition.
As one increases the concentration of a colloidal suspension, the system exhibits a dramatic increase in viscosity. Beyond a certain concentration, the system is said to be a colloidal glass;
Single particle motion in colloidal dispersions: a simple model for active and nonlinear microrheology
The motion of a single Brownian probe particle subjected to a constant external body force and immersed in a dispersion of colloidal particles is studied with a view to providing a simple model for
Microrheology of colloidal dispersions by Brownian dynamics simulations
We investigate active particle-tracking microrheology in a colloidal dispersion by Brownian dynamics simulations. A probe particle is dragged through the dispersion with an externally imposed force