Reversible gelation and dynamical arrest of dipolar colloidsR. Blaak, M. A. Miller and J.-P. Hansen
University Chemical Laboratory - Lensfield Road, Cambridge CB2 1EW, UK
received 20 October 2006; accepted in final form 5 March 2007; published April 2007
published online 28 March 2007
We use molecular dynamics simulations of a simple model to show that dispersions of slightly elongated colloidal particles with long-range dipolar interactions, like ferrofluids, can form a physical (reversible) gel at low volume fractions. On cooling, the particles first self-assemble into a transient percolating network of cross-linked chains, which, at much lower temperatures, then undergoes a kinetic transition to a dynamically arrested state with broken ergodicity. This transition from a transient to a frozen gel is characterised by dynamical signatures reminiscent of jamming in much denser dispersions.
61.20.Ja - Computer simulation of liquid structure.
82.70.Dd - Colloids.
82.70.Gg - Gels and sols.
© Europhysics Letters Association 2007