Spontaneous coarsening of a colloidal network driven by self-generated mechanical stress

Institute of Industrial Science, University of Tokyo - Meguro-ku, Tokyo 153-8505, Japan

Corresponding author: tanaka@iis.u-tokyo.ac.jp

Received: 17 April 2007
Accepted: 6 July 2007

Abstract

Colloidal suspensions can be regarded as an ideal model system for such key daily materials as emulsions, protein solutions, foods, and inks. When colloidal particles strongly attract each other, they aggregate, phase-separate, and sometimes form gels. The basic understanding of this spatially heterogeneous jamming process is of crucial importance from both scientific and industrial viewpoints. Usually it is believed that if colloids attract very strongly with adhesion energy more than 10 times the thermal energy, networks formed by aggregation do not coarsen with time and a stable gel is immediately formed. Contrary to this common belief, we demonstrate by numerical simulation that the coarsening of a colloidal network can proceed by self-generated mechanical stress even without any thermal noise for a system of long-range interactions: fracture-induced coarsening. This remarkable kinetic pathway of purely mechanical origin may shed new light on our basic understanding of the stability and aging (or coarsening) behaviour of colloidal gels.