Issue 17, 2013

Structural arrest and texture dynamics in suspensions of charged colloidal rods

Abstract

There is an abundance of experiments and theories on the glass transition of colloidal systems consisting of spherical particles. Much less is known about possible glass transitions in suspensions of rod-like colloids. In this study we present observations of a glass transition in suspensions of very long and thin rod-like, highly charged colloids. We use as a model system fd-virus particles (a DNA strand covered with coat proteins) at low ionic strength, where thick electric double layers are present. Structural arrest as a result of particle-caging is observed by means of dynamic light scattering. The glass-transition concentration is found to be far above the isotropic–nematic coexistence region. The morphology of the system thus consists of nematic domains with different orientations. Below the glass-transition concentration the initial morphology with large shear-aligned domains breaks up into smaller domains, and equilibrates after typically 50–100 hours. We quantify the dynamics of the transitional and the equilibrated texture by means of image time-correlation. A sharp increase of relaxation times of image time-correlation functions is found at the glass-transition concentration. The texture dynamics thus freezes at the same concentration where structural arrest occurs. We also observe a flow instability, which sets in after very long waiting times (typically 200–300 hours), depending on the rod concentration, which affects the texture morphology.

Graphical abstract: Structural arrest and texture dynamics in suspensions of charged colloidal rods

Supplementary files

Article information

Article type
Paper
Submitted
29 Nov 2012
Accepted
31 Jan 2013
First published
26 Feb 2013
This article is Open Access
Creative Commons BY license

Soft Matter, 2013,9, 4401-4411

Structural arrest and texture dynamics in suspensions of charged colloidal rods

K. Kang and J. K. G. Dhont, Soft Matter, 2013, 9, 4401 DOI: 10.1039/C3SM27754B

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements